Engine/Transmission (1998.5 - 2002) Turbo Codes

[snapshot]

I had Three trouble codes pop up the other day. They were P0234 (engine overboost condition), P0236 (Turbo/Super Boost Sensor A CKT Range/Perf) and P0237 (Turbo/Super Boost Sensor A Circuit Low Input). All three are shown as "pending" codes. Anyoneknow what my truck is trying to tell me?

 

[ThrottleJockey]

What does the boost guage say? How much are you putting out? Is your wastegate stuck closed?

 

[snapshot]

I'm am not sure how to check the wastegate. I see nothing on it externally that should, or could, move. Also not sure how to check out the boost. I ran the eng. up to 3000 RPM and it reads 8. This was done out of gear, so no load. At this time I cannot road test due to too much snow and ash.

 

[rkressg]

On a stock truck, if you exceed more than about 20psi, you will set an overboost code. If the MAP sensor goes bad, it can give erratic readings, causing this. Boost foolers that come with fueling boxes like TST PM3, just limit the amount of boost the ECM sees, stopping this issue from occuring.

Certain oils from air filters such as K&N have been known to destroy these sensors. This was a common issue here many years ago, but I really have not seen this in a long time. It could be the sensor has just died, you can try cleaning with throttle body cleaner or replacing the sensor to see if the issue goes away (assuming you are really not exceeding the amount of boost that the ECM is programmed to handle).

If you are exceeding the limit of boost, you can do two things, 1, get a boost fooler, or check why you are getting excessive boost. The stock HY or HX turbos (I think the 99s all had HY-35 w12cm housings, I can't remember) become inefficient around 35psi (just make more heat beyond that and do not move enough air). If you are staying below that, then you are fine. You will not damage the engine with that low of a pressure. The stock head bolts will hold 50+psi with out an issue.

If it is a stuck wastegate, it can be fixed, but it depends on the type of turbo you have (the HY and HX are different). A quick search here should find what you need depending on the model of turbo you have.

 

[snapshot]

Thanks for the info everybody.

I might mention that I erased the codes and they have not returned (so far)

 

[Devan Manis]

On a stock truck, if you exceed more than about 20psi, you will set an overboost code. If the MAP sensor goes bad, it can give erratic readings, causing this. Boost foolers that come with fueling boxes like TST PM3, just limit the amount of boost the ECM sees, stopping this issue from occuring.



Certain oils from air filters such as K&N have been known to destroy these sensors. This was a common issue here many years ago, but I really have not seen this in a long time. It could be the sensor has just died, you can try cleaning with throttle body cleaner or replacing the sensor to see if the issue goes away (assuming you are really not exceeding the amount of boost that the ECM is programmed to handle).



If you are exceeding the limit of boost, you can do two things, 1, get a boost fooler, or check why you are getting excessive boost. The stock HY or HX turbos (I think the 99s all had HY-35 w12cm housings, I can't remember) become inefficient around 35psi (just make more heat beyond that and do not move enough air). If you are staying below that, then you are fine. You will not damage the engine with that low of a pressure. The stock head bolts will hold 50+psi with out an issue.



If it is a stuck wastegate, it can be fixed, but it depends on the type of turbo you have (the HY and HX are different). A quick search here should find what you need depending on the model of turbo you have.

Mine popped at fourty.

 

[snapshot]

My air filter is stock so oil in the filter should not be a problem.

How would I exceed 20psi? over rev or ???

My engine is stock and I very seldom exceed 60 mph, maybe only when passing. Alaska roads are not that friendly.

What exactly does it mean when the codes are all listed as "pending"?

Where is the MAP sensor located and can it be replaced without too much trouble or skill. Are they very expencive?