Engine/Transmission (1998.5 - 2002) Intake temperature sensor

[WMonroe]

My brother in law just bought a 99 2500 that has tripped a check engine light. He pulled the code and it is for "intake temperature sensor". He said the truck runs fine except for the check engine light and he is only getting 8 mpg :--) . He hasn't had it long enough to get a baseline for fuel mileage but all of his driving is empty with just the truck so it should definately be higher than 8mpg. Is this just a bad sensor that needs replaced or is there something else going on?

Info on the truck:

1999 2500 Reg cab. automatic 3. 55 gears Injection pump recently replaced (before he bought it). fuel pressure 13-14 psi at idle and no lower than 11psi.

He is getting "normal" egt and boost readings.

Thanks in advance

Will

 

[trqmnstr]

I would clean it before you replace it and see if that helps. Just spray it with some brake cleaner and make sure it's dry before you reinstall.

 

[davemac]

This might help.



http://www.dodgeram.org/tech/dsl/sensors/IAT/clean.htm

 

[WMonroe]

Thanks for the suggestion and the link. Hopefully he just need to clean or replace it and that will solve the problem.

Will

 

[WMonroe]

Well he bought and installed a new sensor, but the check engine light is still coming on. He said on the old one that the plastic cage was starting to disintegrate. The code is coming up as "low input voltage". Any ideas what would cause low voltage to the sensor? Or any other ideas?

Thanks

Will

 

[nps]

ECM or wiring. What it is saying is that the ECM is reading too low of an input voltage from the IAT. Translated, the IAT is putting out too much resistance (open wires), or the ECM isn't feeding it any voltage to read back.



Did you check the IAT resistance on the bench before install? It should always read somewhere between 3K ohms and 20K ohms. If it is open, then its bad.



When I picked up and IAT from the local Cummins store it was obvious that the unit they were trying to pass off to me as new had been installed - greasy with knurl marks on the flats (these things are usually finger tight). Told them to try again - may work when they are parts-swapping in the shop but not over the counter.



The Dodge dealer is cheaper than Cummins on this part, but you have to order it from the warehouse (at least my local 5 star does not stock it).

 

[WMonroe]

Thanks for the reply. I'm not sure if the resistance was checked or not.



Does anyone know any reliable shops around Champaigne Illinois to take the truck to if he can't figure it out?



Thanks

Will

 

[brianv31]

I'm the brother-in-law with the '99 IAT sensor in question. Local 5-star, after many "discussions" with Chrysler, determined the ECM was bad. Couldn't ask for a better opportunity to replace it with a catcher ECM, so that's what I did. Cleared the codes after replacing the stock one and haven't had it come back since. I would highly recommend the catcher ECM.