Hi, I have a 98 GMC Jimmy, the engine light has been comming up for a while giving me codes P0401 & P0402, i would reset the code and the vehicle would work fine for a week or two, the last two days the engine light comes up every couple of minutes and gives me a code of P0101, for all the codes just before the engine light comes on the vehicle will buck and rev higher and higher before it changes gears, the weather makes no difference. Also when the weather gets cold my mileage drops from 425-450 kms per tank to 200-220 kms per tank, i understand in the winter the mileage will change but I never had a vehicle that would drop this much. I baby drive this vehicle because of the mileage any help please.....
98 gmc jimmy help
- Thread starter gunner44
- Start date
Molson02536
New member
P0101 is a MAF sensor issue, start with the simple and inspect the wire leads to the sensor. Once determined that the wire leads are good, clean the MAF sensor with MAF cleaner that you can buy from most Auto Parts store like Auto Zone.
The P0401 and P0402 are EGR valve related.
P0402 - Exhaust Gas Recirculation Flow Excessive Detected, Basically the exact opposite of P0401 - Exhaust Gas Recirculation Flow Insufficient Detected.
The diagnostic steps will be somewhat similar to the MAF sensor. P0401 and P0402 is typically caused by an EGR valve that is stuck open by a chunk of carbon.
Remove the EGR valve and clean it. When you reinstall it, do so with a new gasket. There is an aftermarket gasket that has an integrated screen that decreases the possibility of this happening again.
Good luck and keep us posted.