Engine/Transmission (1998.5 - 2002) 2002 engine code - P0126

[Jake The Snake]

I have been having a problem with my truck having what I would consider a "limp mode" incidents. This limp mode is characterized by the truck starting ok all the time but intermittently when you put it in gear the truck will not take trottle input for some duration, usually less than 1 - 2 minutes, it will stay running but will accelerate only very slowly.



After a "limp mode" incident occurs and is over the truck will suddenly spring to life and run normally for the duration of the trip regardless of the distance. This does not happen all the time but it is really inconvenient and I don't know whether it is going to stay in limp mode.



The truck has about 122,000 miles and gets what I consider excellent maintenance and I have owned it since it was new. I have a Hypertech handheld programmer that I use to check for codes from the OBDII port. The code that was thrown was a P0126 (Insufficent ECT for stable operation)according to the programmer but that code is not seen in my factory manuals so I need a little guidance. I replaced the fuel filter and oil filter and after I was done I reset the P0126 code with the programmer and so far after 5 starts and subsequent trips no repeat of the limp mode has occurred but as I said it is intermittent and probably is still an issue.

 

[cerberusiam]

P0126 Insufficient Coolant Temperature for Stable Operation



Now exactly how the ECU is using is another mystery. Possibility that the coolant temp sensor is not working correctly or the connection is bad. The engines normally derate at cold operating temps so you need to get some heat into them so they will fuel correctly.



Is cold temps a factor in this happening and how cold?

 

[jeepit]

That's behaving like TPS problem.

 

[Jake The Snake]

Cerberuiasm and Jeepit,



Thanks for the replies. I am unsure what TPS is so help me out. As for the nature of how cold is it when this happens, it is not real cold most of the time when this occurs. I live in the part of the country where it does get real cold sometimes but I have started and run the truck when it is - 15 degrees F and it starts well with two consecutive engine air heater cycles and the "limp mode" doesn't happen. The other day it was about 20 degrees F and it happened 2 times within 3 hours after a 45 minute run to work. It doesn't seem to be temperature dependent although it doesn't seem to happen in the summer weather. Go Figure?????



If you have other input I am all ears. Your responses are the reason that TDR is such a great "club" to belong to. Thanks for all the assistance.



Jeepit, I also have a Lance camper model 821. How long have you had yours?

 

[cerberusiam]

Not TPS but APPS problem. Accelerator pedeal position sensor, it is what tells the ECU how much fuel to give the engine. When the APPS goes bad and gives the ECU bad info it won't fuel the engine correctly.



Normally you get codes indicating APPS signal is high\low for to long and its obvious it is the APPS. It is also possible the APPS is causing the problem and the ECU thinks it is the engine temp. The ECU is good at doing things when all the parameters are correct, lousy at resolving problems.



It could be something simple like a sensor or more complicated like the ECU. It it was me, I would replace the coolant temp sensor, chacke all the grounds and connections, load test batteries and check battery connections. If that did not help, an APPS is $170 for the next step.

 

[jeepit]

cerberusiam,

Thanks for the correction.

TPS Throttle Position Sensor

APPS Accelerater Pedal Position Sensor