Jeep Grand Cherokee Scanned P1281 Fault Code

9:01 am Apprentice Tech, DIY, How To Auto Repair, Jeep, Service Writer


2003 Jeep Grand Cherokee 4.0 Liter Engine with a P1281 Code.

This automotive repair article is on a specific check engine light code for a Jeep Grand Cherokee. When scanned with an automotive scan tool, a P1281 fault code was retrieved. The code has to do with the engine not reaching operating temperature within a certain length of time after the vehicle has been started. For the catalytic converter to operate at it’s best the engine needs to reach it’s normal operating temp. The cooling system’s thermostat normally stays closed when the engine is cold, allowing the motor to warm up quickly. That’s why the trick of removing the thermostat to let the car run cooler, like back in the 1970’s (prior to on-board computers) doesn’t work well anymore.

Back to repairing this specific vehicle. In most cases, a P1281 fault code like the one that caused this CEL (Check Engine Light) to come on; means that the thermostat is either stuck open, or that it has simply fallen apart. In either case it is no longer capable of closing and it cannot stop the flow of anti-freeze throughout the cooling system. This keeps the engine from reaching the normal temperature range within the expected time-frame. When the optimal range is not obtained, the fuel mixture will be too rich, the fuel doesn’t burn as well and catalytic converters aren’t as efficient. Other things can even be affected like the transmission shift points. Shift points may take longer to reach, making the engine wind out more to warm it up sooner.  Jeep_Grand_Cherokee_2003_Thermostat   This thermostat is an easy one to change. As can be seen in the image above, the thermostat came out in pieces. Before installing a new thermostat, the old gasket material must be cleaned one of two ways. 1. With a gasket scraper (old school).  or 2. A roloc type scotch grinding disc and a 90 degree die grinder. Most gaskets for this application have self adhesive backings to help hold them in place. If the gasket doesn’t have adhesive, a little 3M glue can be used to hold everything in place until the bolts can be secured. One mistake made by beginners and by professional techs that get into too much of a hurry,  is to allow the replacement t-stat to fall out of the recess while installing it. If the thermostat housing is tightened up with the thermostat out of position, the housing can be cracked easily. Other than that,  it is a pretty straight forward job. After replacing the thermostat, a Lisle coolant funnel can be used to help burp the air out of the cooling system and fill the over-flow reservoir. Once that is done it’s time to clear the code with a scan tool or code reader.

Question: Is there anything else that could throw a P1281 fault code?

Answer: In most cases it will be due to a bad thermostat, but yes. A faulty temperature sending unit could possibly fool the computer into thinking that the engine did not warm up properly. They have this one worked out pretty well though. The computer is likely to get suspicious of an engine that has been running 20 minutes and still hasn’t reached normal operating temperature.

More about suspected false readings from gauges.

When I suspected a false temperature reading, I would always check with my Genisys scan tool and monitor the data screen. Sometimes there will be two sensors, one for the gauge and one for the computer. I would compare the reading on the data screen and the temperature on the car’s gauge. These readings should be about the same, so if there is a huge difference in the readings then, one is most likely faulty or the gauge itself could be reading inaccurately.

Question: I’m a service writer and many times when I try to get a thermostat covered under an aftermarket warranty the claim is denied. What is the best way to describe the cause and correction to have the best chance of getting this covered?

Answer: I would write this up the following way to provide the information the warranty company needs to make their decision.

Concern: Customer states the CEL (Check Engine Light) is on.

Cause: Scanned P1281, thermostat malfunction indicated. Engine takes too long to reach operating temperature. Verified the thermostat is stuck in the open position – vehicle has no impact damage or aftermarket modifications.

Correction: Installed replacement t-stat and replenished coolant. Cleared code and retested to verify repair and correct concern. 

66 Responses
  1. ebookdemo :

    Date: August 21, 2009 @ 11:34 am

    You are life saver, found it via google.

  2. Eric :

    Date: October 25, 2010 @ 6:17 pm

    So I just got this code after recently replacing my thermostat (two weekends ago, maybe three), which didn’t fix the overheating problem I was having in stop-and-go situations. It doesn’t overheat at highway speeds, though, only under stop-and-go. Any thoughts?

  3. dennisb - Auto Tool Sales :

    Date: October 25, 2010 @ 6:44 pm

    Eric, usually the symptom you described of “overheating at stops” and NOT when moving at faster speeds is usually because of a radiator cooling fan not working properly. When you’re on the highway, the wind is cooling the radiator and no fan is needed.

    The P1281 fault code is not for overheating, it’s for it not heating up quick enough, so the that part does not make sense.

  4. Eric :

    Date: October 26, 2010 @ 6:23 pm

    Thanks Dennis. I have the repair manual, I guess I’ll look through there and see if I can find how to troubleshoot the fan.

  5. Epyon777 :

    Date: June 5, 2011 @ 9:49 am

    Hey, I’ve got a 01 jeep g.c. Laredo, 4.0. I got this code and swapped the thermostat. The code reappeared, so I swaped the temp sender. again the code popped up. Any ideas on where i should go from here?

  6. dennisb - Auto Tool Sales :

    Date: June 5, 2011 @ 1:41 pm

    99% of the time it is the thermostat. Make sure the correct t-stat is being put in, I would opt for a dealer one if possible. Also make sure the coolant is full and no air in the system. You may have to take to the repair shop for further diagnosis if the problem persists. Good Luck

  7. wisertime :

    Date: August 8, 2011 @ 9:24 pm

    Hey, I’ve got an 04 GC with a 4 liter, CEL came on a couple of weeks ago and I ignored it (it’s had a history of throwing lights, only to have them go off a week or so later), but light’s stayed on. Today, jeep started overheating when idling for more than minute or two (it was 100 here today). Fan spins, no coolant leaks – I originally thought thermo, found where it’s also throwing 1281 code. Found this site looking for links between the two (like Eric above). So you don’t think code/overheating could both be caused by same inop thermostat? It’d be weird to have two similar issues pop up though within a week or so of each other, so seems like they should be related – at least to me. Going to swap thermostat first, what are chances it will correct both?

  8. dennisb - Auto Tool Sales :

    Date: August 9, 2011 @ 6:48 am

    The P1281 fault code is not for overheating, it’s for it not heating up quick enough.

    Your may be spinning but not spinning at a high enough speed.

    You’ve got nothing to lose by changing the thermostat out again… and seeing if it takes care of both problems. My guess is that it won’t. Good Luck.

  9. mike :

    Date: November 9, 2011 @ 3:44 am

    my suv is reading this code p1281 but the temperature gauge looks fine what could be the problem in this case

  10. dennisb - Auto Tool Sales :

    Date: November 9, 2011 @ 6:24 am

    Mike, the P1281 trouble code most likely means the thermostat is stuck open not forcing the engine to heat up to operating temperature as quickly as the computer would like to see. The temperature gauge can look fine but if operating temperature is not achieved with a certain time limit (or parameter) this code will be set. Good Luck.


    Date: May 30, 2012 @ 7:47 pm

    I wanted to thank you for the help. I have this problem with my Jeep and I will change the thermostat. Hoping that’s the problem. Thanks again.

  12. Cristina :

    Date: June 19, 2012 @ 10:18 pm

    I have that code on my Jeep 2000 and I’m having issues with my revolutions (RPM’s will vary) and also pop at times would you know if tht may be my transmission.

  13. dennisb - Auto Tool Sales :

    Date: June 20, 2012 @ 7:09 am

    Cristina, I would the thermostat issue and go from there. However, what you are describing could be a CKP (Crank Position Sensor) starting to fail. Good Luck.

  14. jesse :

    Date: August 8, 2012 @ 12:11 pm

    i have 2003 GC about a week ago gave me 0320 i had the crank sens replaced (by a pro). this morn on the way to work check light came on gave me an 0320 and 1281 any thoughts on how these could be related? how could a crank sensor go out so quickly.

  15. dennisb - Auto Tool Sales :

    Date: August 8, 2012 @ 12:58 pm

    Jesse, I would say they are not related to each other. I would ask the pro to double check his diagnosis and repair. There could be a wire chafed or maybe he didn’t space the sensor far enough away from the flywheel. The sensor comes with a small piece of paper attached to it to space it. If this was removed prior to installation, the sensor could have been damaged from touching the flywheel. Good Luck.

  16. amy :

    Date: August 24, 2012 @ 11:05 am

    my CEL has been on and reading this code for a bit, but all the sudden my jeep has hesitation when starting. could this be related?

  17. dennisb - Auto Tool Sales :

    Date: August 24, 2012 @ 11:06 am

    Amy, No, not related. I would check the battery. Good Luck.

  18. Regina :

    Date: October 12, 2012 @ 7:41 pm

    My engine light came on today and I had it tested. I have a code P1281. I have a 2003 Jeep Grand Cherokee 6 cylinder. I was also low on Anti-freeze which I added. Please tell me if that was the reason for the engine light?

  19. dennisb - Auto Tool Sales :

    Date: October 13, 2012 @ 8:18 am

    Regina, the most common cause of the P1281 code is covered in the repair article above. I would pressure test the cooling system and look for a reason (leak) that would explain why the system was low. Repair the leak, make sure the thermostat hasn’t fallen apart like the one pictured above, clear the code and retest. Good Luck.

  20. larry :

    Date: October 14, 2012 @ 5:24 pm

    Thanks for the information I was getting the 1281 code after I added fluid to the radiator because my radiator needs fluid after only a week and The radiator is new. I have no leaks I understand the thermostat but why the low fluid all the time?

  21. dennisb - Auto Tool Sales :

    Date: October 14, 2012 @ 6:23 pm

    Larry, coolant either leaks externally or inside the engine. I would pressure test to see if there’s an external leak like a water pump, radiator hose or something like that. What can also happen but less often is a head gasket leak. Which may cause a leak inside the engine. If this happens, the coolant gets burned inside the engine and in the catalytic converter possibly leaving no signs. A carbon test for the cooling system may help determine if this is the problem. Good Luck.

  22. Mike :

    Date: November 27, 2012 @ 6:56 pm

    This is a good thread. On my 2000 GC with the 6 cyl engine, I am getting the 1281 code. I am monitoring the ECU temperature signal with a diagnostic display (DASHDAQ), and the computer temp moves with the gauge, and seems to get hot quite rapidly. Also, when I clear the code, then read codes, the code is back immediately. Shouldn’t it wait until the next start to give me the code again?

  23. dennisb - Auto Tool Sales :

    Date: November 27, 2012 @ 7:11 pm

    Mike, you are right it should not come back that quickly. I would try clearing the code with a different tool. I suspect that the tool you are using is not actually clearing the code. Good Luck.

  24. jesse :

    Date: December 2, 2012 @ 4:20 pm

    2003 GC 4.0 just replaced thermostat heater only blows at higher rpm’s. i think maybe air in the system but not sure please help.

  25. dennisb - Auto Tool Sales :

    Date: December 3, 2012 @ 7:19 am

    Jesse, you are on the right track. I would bleed the air out using the bleeder screw on the t-stat housing (if yours has one). Also running the engine and squeezing the upper radiator hose helps to burp the air out too. Good Luck.

  26. jesse :

    Date: December 4, 2012 @ 4:51 pm

    lol thanx Dennis, I actually figured out the trick with hose by accident. A little over 2 hundred miles and no probs so far.

  27. Marcelino :

    Date: December 5, 2012 @ 10:01 pm

    I have a 2003 Jeep GC with a 4.0. I have replaced the fan relay 5 times this year and they all stop working. The most recent one worked for only one week. What causes this? I get a code P1491 with an AutoScanner Plus. This casused the radiator to exploded when I took the car in to Smog.

  28. dennisb - Auto Tool Sales :

    Date: December 6, 2012 @ 12:33 pm

    Marcelino, if the fan motor draws too many amps it may cause the relay or module to fail prematurely. Good Luck

  29. Marcelino :

    Date: December 6, 2012 @ 10:39 pm

    How does one measure the amps the coolant fan is drawing? What are the limits?

  30. dennisb - Auto Tool Sales :

    Date: December 7, 2012 @ 6:26 am

    Marcelino, You could use a multi meter with an amp probe, not sure if you will find the specs in a repair manual. I would manually check the the motor for wobble or tightness. The fan shouldn’t move from side to side excessively and the motor should spin pretty freely by hand. Other than that, the fact that the relay has burnt out repeatedly, would be reason enough for me to replace the fan motor anyway to eliminate that as the cause. Good Luck

  31. Marcelino :

    Date: December 27, 2012 @ 12:31 pm

    Thanks Dennisb. I did not mention that I had already replaced the fan motor. But, you got me thinking so I check the connector and noticed that one of the pronges was pushed in further that the other three so I took some needle nose pliers an pull it back lining it up with the other three replaced the relay again and it has been working for almost a month. I changed the tstat which was locked open and the trouble light reset it’s self. The vehicle has since passed smog. Once again thanks.

  32. Marcelino :

    Date: December 27, 2012 @ 12:41 pm

    Dennisb: I have a 1999 Jaguar Vanden Plas with a 4.0 that stalled at an intersection. The symptoms are that of a fuel pump which I replaced approximately 8 months ago. I used a scanner to test it but inadvertently cleared the codes. Now it produces a P1111 code. However, it also indicates to replace the Purge valve switch. I not sure that would prevent the car from starting. Because I cleared the codes I don’t trust the scanner since the car has not run at all after clearing the codes. Should I replace the pump again? It involves a lot of work. I do hear the pump run for a second or two after turn on the ignition but it is a loud humm sound. Suggestions.

  33. dennisb - Auto Tool Sales :

    Date: December 27, 2012 @ 1:08 pm

    Marcelino, the P1111 is means diagnostic cycle is complete. So that’s not a problem. I would check for fuel pressure before ever condemning a fuel pump. Good Luck.

  34. Marcelino :

    Date: December 27, 2012 @ 7:08 pm

    I checked for pressure at the fuel rail. No pressure at all. I sprayed starting fluid in the air intake trottle body and the car starts then turns off when the starting fluid dissipates. Is there anything other than the fuel pump that causes this? The fuel filter was replaced when I replaced the pump eight months ago. I don’t see any kinks in the lines.

  35. dennisb - Auto Tool Sales :

    Date: December 28, 2012 @ 7:04 am

    Marcelino, I would check for power and ground to the fuel pump when trying to start. To answer your question about anything else that could cause it – sure, lots of things like faulty wiring, bad crank sensor etc. could cause this if there’s NO power to the pump. To check the crank position sensor, I would check the RPM’s either on the dash gauges or with the scan tool on the data screen when cranking the engine over. Usually, if the crank sensor is bad no RPM’s will register. Good Luck.

  36. Ernest :

    Date: January 4, 2013 @ 10:00 pm

    I recently got the code p 1281 on my 2002 Jeep grand cherokee and I was wondering if that code would cause the Jeep to consume more fuel than usual, cause it’s wasting an insane amount?

  37. Jim Kauffman :

    Date: January 28, 2013 @ 10:49 am

    You might mention that you can find the temp the to thermostat should start to open normally on the tip that is facing the engine. You then can stick the thermostat in a pan filled full of water, and add a candy thermometer to check the water temp. As you heat the water, you should see the thermostat start to open at the temperature noted on the thermostat. If I buy a new one., I always use this method prior to installation to ensure I’m not wasting my time.

  38. Nia :

    Date: March 21, 2013 @ 10:41 am

    So I have a lemon of a Jeep. Its an 2002 Liberty Sport, 2.4, stick shift. The check engine light has been on a long time. First I was told it was “too cold too long.” Then we got a diagnostic scan and it came up “P1281 – manufacturer control fuel air metering”. I changed the thermostat out twice, I have had a new radiator put in, there is no heat no matter how long it runs (and its the middle of winter) and watching the temp gauge, it never gets up to temp. But ALSO, it has a really really hard time starting. It turns over…and over and over and over, then when it finally starts, it spits and sputters like its not getting proper fuel. So with this code (p1281) I’ve got two different descriptions of what it means and I’m having problems linked to both descriptions. Which one is it? Since I already did the thermostat what should I do next? And if it does have something to do with the fuel/air metering, where do I start? Please and thank you :)

  39. dennisb - Auto Tool Sales :

    Date: March 21, 2013 @ 11:00 am

    Nia, The definition has to do with the engine not reaching operating temperature within a pre-determined amount of time (parameter). Most of the time it’s because of a bad or broken thermostat that is not restricting the flow of coolant long enough for the engine to heat up quickly. If the incorrect thermostat, like a one that opens up too soon, is installed the same code could return. Sometimes aftermarket t-stats are available that open at lower temperatures, like 180 degrees. I would put a factory thermostat in and try that. I think the OE (Original Equipment) one is going to open around 200-205 degrees. As far as the hard start issue, this would be something unrelated. Possibly the fuel pump not holding pressure after the vehicle sits awhile. The fuel pressure in the lines may bleed down. I would do a pressure test to verify, in case the fuel pressure is bleeding down below specifications when the engine is off. That would cause a long crank time before starting while the fuel pressure is building back up. This is a very common issue with Grand Cherokees and may also occur with the Jeep Liberty. Good Luck.

  40. Nia :

    Date: March 21, 2013 @ 11:08 am

    Just out of curiousity, when the diagnostic test came up with that code, any idea why did it describe it as manufacturer control fuel air metering? I guess thats where a lot of my confusion was coming from because the tool said one thing and all the other information i’ve been reading is saying it has to do with tempurature. I think i’ll be spending the weekend in the garage!

  41. dennisb - Auto Tool Sales :

    Date: March 21, 2013 @ 12:23 pm

    Maybe a glitch in the software for the scan tool? You may want to address that question to the tool manufacturer. Good Luck.

  42. Fernando :

    Date: April 27, 2013 @ 1:32 pm

    I have a 2003 JGC Laredo. It will try to start but won’t. Put a scanner on it and came up with p1281. Replaced t-stat and cooling fan relay. Started it up let it run for twenty mins.then it shut off. Put scanner back on and it reads 0 codes. Did a hard reset, thing still won’t start. Could it be faulty starter, crank sensor?…

  43. dennisb - Auto Tool Sales :

    Date: April 27, 2013 @ 3:18 pm

    Fernando, the P1281 is typically for the t-stat which will NOT cause a no start condition. The starter would cause the engine not to crank over and would not cause the engine to shut off and running twenty minutes. The crank sensor can cause a no start condition and could cause the engine to shut off randomly. When the problem is occurring, I would check the data screen to see if RPM’s are registering. Besides that, I would check for fuel pressure, spark and fuel injector pulse. All the normal suspects. Good Luck.

  44. Brant :

    Date: August 8, 2013 @ 7:34 pm

    dennis, I have an 02 jeep liberty. timing belt broke and I had the motor rebuilt and changed out all major components… including the thermostat. I get a very slight studder in the trans or motor when driving under normal conditions. only I can feel, because im the only one who drives it everyday. that issue started after about 500 miles on the REMAN motor. I got the P1281 code after about a 1000. thermostat could possibly be sticking like you said, but I just replaced it, so I replaced the coolant temp sending sensor. after resetting the light, it came back on after a normal cycle, 2 days. im guessing thermostat or the entire thermostat housing with new sensor? hopefully that would take care of both issues but doubt it. what you got for me? thanks!

  45. dennisb - Auto Tool Sales :

    Date: August 9, 2013 @ 8:07 am

    Brant, sometimes vehicle owners are over-sensitive to vibrations after they have had extensive work performed. Not saying that you are over reacting to the slight studder, but I wouldn’t look for problems that are very slight and hardly noticeable. If it’s a real problem it may get worse and trigger a code presenting itself and making it obvious.

    As far as the P1281, this will not cause a studder. It will only cause the engine to NOT go into closed loop as quickly as it should. Since you have already replaced the thermostat, I would suspect a faulty one or one that has an incorrect temperature. I would make sure the t-stat that I install is the OE one or at least the OE temp designation. Good Luck.

  46. Mike :

    Date: December 11, 2013 @ 7:20 pm

    Hello and thanks for the help. 2003 Jeep Grand Cherokee. Low Coolant Warning light came on recently (despite fact that coolant wasn’t low). CEL came on a few days later and threw P1281. I replaced the thermostat. Noticed that the old one did indeed appear to be stuck in the open position. Cranked car and test drove expecting to have solved problem. To my dismay, the engine temp never rose above 1/4 according to gauge and no heat. The CEL light is still on (wouldn’t it go off if problem was solved) and the low coolant light is on. All of these things are related somehow, just not sure how. I’m unsure of what else to try next? Any help would be appreciated.

  47. dennisb - Auto Tool Sales :

    Date: December 12, 2013 @ 10:39 am

    There’s a sensor in the coolant reserve bottle that could be stuck or faulty. The code is normally cleared with a scan tool after a repair has been made. The light will eventually go off after several drive cycles if the problem has been resolved. The gauge on the dash could be wrong. I would double check with a scan tool looking at the data screen. The temp listed on the data screen uses a different temp sensor than the dash gauge. Likes on Facebook are appreciated. Good Luck.

  48. liz :

    Date: February 26, 2014 @ 7:21 pm

    I just want to say you are very knowledgable and very patient. Nice to see this forum.

  49. dennisb - Auto Tool Sales :

    Date: February 27, 2014 @ 7:15 am

    Liz, it’s about time someone noticed! Now buzz off!! I’m just kidding…

  50. Ruben :

    Date: March 7, 2014 @ 10:49 am

    Hi, I have an 04 JGC SE 4.0 V6. About a week ago the CEL appeared I took it to auto zone for a scan and these three codes came up:

    1281 engine is cold to long
    p0455 large leak detected
    p0422 catalyst efficiency low-bank 1.

    So I started with replacing the thermostat a murray 3009 (Deg F): 195. Motor seems to be reaching about 200 (deg) and code continues to appear along with the other same two codes. So my questions is what seems to be the issue here and are the three codes related in some way since they all appeared at the same time?

    Also I did notice a damp spot on the ground coming from muffler while vehicle is on I verified it’s not oil it seems to me like condensation.

  51. dennisb - Auto Tool Sales :

    Date: March 7, 2014 @ 11:25 am

    Ruben I would say the codes are not related because they have to do with different systems. If you did not clear the code after replacing the thermostat it will take awhile (several trips as defined by Jeep). The P0455 is usually a bad gas cap seal or because the gas cap was left off completely. Other reasons can be because of rubber hoses deteriorated and leaking in the evaporative system. The P0422 is usually for a catalytic converter that is no longer working sufficiently. Good Luck.

  52. Meredith :

    Date: May 17, 2014 @ 6:58 pm

    I have a 1999 Jeep Cherokee 4.0 with a P1281 code. My scan tool shows this as P1281 Accelerator Pedal Position (APP) Sensor 2 Performance.

    I know you are saying P1281 is too long for coolant to reach operating temperature. Is it possible that for different years the code meant different things?

  53. dennisb - Auto Tool Sales :

    Date: May 17, 2014 @ 8:00 pm

    No, not in this case. Some codes if they are manufacturer specific could mean different things from manufacturer to manufacturer but not within one manufacturer. It’s more likely that your scan tool is just incorrect. There’s a lot of China scan tools that are great. Then there are a lot of China scan tools that aren’t so great especially when they have been backwards engineered to copy another scan tool. I would personally check the thermostat, it’s probably fallen apart. I’ve replaced a lot of these when I worked at Carmax on Jeep Grand Cherokees and regular Classic Cherokees. It’s a common problem which has a very highly documented failure pattern. If you would rather do some more testing before pulling the thermostat you could have the codes checked with another scan tool. Many places will check codes for free or pretty inexpensively. Good Luck.

  54. Jim :

    Date: October 17, 2014 @ 6:49 am

    I have a 2002 Jeep Grand Cherokee that I got codes for bad 02 sensors. I replaced all four and cleared the codes with an OBII diagnosis tool but the codes come back right away. They are all new sensors and installed properly. Wiring and plugs appear good. What can I do to clear the codes?

  55. dennisb - Auto Tool Sales :

    Date: October 17, 2014 @ 7:57 am

    Jim, we have other auto repair articles that are about o2 sensors, this is not one of them. See those O2 articles for more information. Obviously though, O2 codes don’t necessarily mean the Oxygen sensors are bad as you’ve discovered the hard way. The actual codes that your vehicle is setting, are the best clue to what the problem is. If you know the exact codes, research possible causes. Could be an exhaust leak, vacuum leak, a bad catalytic converter etc. Good Luck.

  56. bsaiso :

    Date: January 25, 2015 @ 3:20 pm

    Dear Sir, I bought a 2007 commander Hemi 5.7L, I noticed that there is no red or blue colored lines on the air blowing outlets and it blows cold air when I want warm, I’m confused.

  57. dennisb - Auto Tool Sales :

    Date: January 26, 2015 @ 7:49 am

    The controls are not complicated. So, the heater must not be working. I’d check the heater. Although there can be many reasons, low coolant is the most common cause of the heater not working. Good Luck.

  58. Jessica :

    Date: June 22, 2015 @ 10:02 am

    I have a 04 jeep grand Cherokee lerado, straight 6, 2wd I had recently changed the thermostat in my jeep because when i would turn on my a/c it would over heat my engine (past 210 all the way to max out) Any ways i put in a fail safe 195 thermostat. Ever since I changed my thermostat my temp runs on the line between 100 and 210 while driving, when stopped or parked my temp goes up to 195. well the other night i was taking a long drive on the interstate and my check engine light came on. read code 1281, again my engine was on the line in between 100 and 210 when the light went off… Any answers as to what could be causing this issue?

  59. dennisb - Auto Tool Sales :

    Date: June 22, 2015 @ 10:16 am

    Jessica, I wouldn’t think that a thermostat would have been you problem in the first place, but it most likely is now. I’d try a factory thermostat, since the aftermarket one may not be working as expected. Also make sure that all the air is out of the cooling system and the coolant is full. Good Luck.

  60. Jessica :

    Date: June 22, 2015 @ 10:29 am

    Actually it was, the thermostat was stuck open, and had a leak a small one but still and it was 11 years old (well i think it was, i bought the jeep recently from a private owner). What is the difference between a dealer thermostat and one from auto zone?

  61. dennisb - Auto Tool Sales :

    Date: June 22, 2015 @ 10:43 am

    A stuck open thermostat would not be the cause of an overheat. A stuck open thermostat would cause the engine to NOT reach normal operating temperature in the predetermined parameter that the computer checks, which would result in the code P1281 coming back. You didn’t mention the code or the fact that the thermostat was stuck open, so I assumed that wasn’t the issue you were having. Especially since all I did know was that you were replacing it for an overheat condition which didn’t make sense. The small leak was the main issue for the overheat. The failsafe thermostat is designed to stick in the open position if ever overheated causing the code P1281 to come back. The factory thermostat’s are typically better quality and are designed to open and close at the proper time which would avoid failed tests when the computer does it’s self systems checks.

  62. Jessica :

    Date: June 22, 2015 @ 11:29 am

    Ok there is a misunderstanding here. So it all started with my jeep overheating when i used the a/c, and i didnt have a check engine light. When we changed the thermostat we noticed the thermostat was stuck open didnt even close after being out of the vehicle for over 4 hours, noticed that there could have possibly been a small leak but nothing visible. i changed the thermostat monday 6-15-15, noticed that the jeep would run on the line between 100 and 210 while driving and would slowly go up to 195 while parked or the temp would go up slightly while stopped. saturday night driving 6-20-15 the check engine light came on and gave me the error code P1281. when i have my a/c on the temp does go up a tad from the line between 100 and 210. I checked my ac unit with dye and no leaks. I dont know what else would have caused my jeep to over heat with the a/c on only. again now i have this error code after fixing my thermostat it has not over heated since i changed it. do you know what would cause it. and what is the difference in thermostats from the dealer and one from a part store? and it is that jeep during that time made it to where you can only use a dealer thermostat?

  63. dennisb - Auto Tool Sales :

    Date: June 22, 2015 @ 12:15 pm

    Jessica, there should have definitely been a code if your thermostat was stuck open. You may find an aftermarket thermostat that won’t cause a problem. It’s been my experience that when having thermostat related issues, it’s best go back with the original equipment one from the dealer.

  64. Javier Q :

    Date: July 26, 2015 @ 9:24 am

    Hello Dannis I have the same problem. I have grand cherokee 2002 the code only come on when I drive in the highway. When I drive on the street all working fine. I reset the computer by disconnecting the land wire and after 40 miles driving on the highway the code p1281 come on again. I just changed the thermostat and the code came again

  65. dennisb - Auto Tool Sales :

    Date: July 26, 2015 @ 9:33 am

    Resetting the code does nothing to fix the problem. After the vehicle has been driven long enough for the computer to run self tests and sees a failed one the code will come back and light is turned on. I’d try a factory thermostat and see if that takes care of the problem. Be sure all the air is out of the system and there’s no leaks. Good Luck

  66. Mauricio :

    Date: August 17, 2015 @ 3:35 pm

    Muchas gracias por este articulo

    ..muy explicito he informativo..saludoa

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