Reduced Engine Power
Asked by TyWallace7 Jul 28, 2019 at 03:09 PM about the 2008 Pontiac Grand Prix Base
Question type: Maintenance & Repair
Ive replaced the throttle body, 20 way connector harness
and the gas pedal..Still getting Reduced Engine Power
code..Any suggestions? Replaced with all new parts
8 Answers
Did you try the throttle/idle relearn procedure? That should be done of throttle was replaced
TyWallace7 answered 5 years ago
Yes i started for 3 minutes, sat off for 1 minute, started back up for 3 minutes..It drove for a while but went back into Reduced engine power limp mode
TyWallace7 answered 5 years ago
Yes the evap P0449 and of course the throttle body and pedal position sensor comes back with that in limp mode Reduced Engine Power..Ive put 2 new pedals, Tps, Throttle body new and a 20 way connector harness..I dont know wut role an Evap vent valve/ Canister/ solenoid circuit will play if any..But i hav that new to put in also..If not that then maybe a faulty wiring
After clearing the codes they come back right away or after some time?
TyWallace7 answered 5 years ago
After i drive and the temp gauge gets to normal they come back every time..Thats wut baffles me..It cleared once i replaced all the required parts..I drive a while til the car gets to normal running temp and then it makes all the codes return associated with Reduced Engine Power (gas peda/ sensor....throttle body/ sensor)??
I don’t see the EVAP causing the reduced engine power issue. EVAP canister solenoid really only comes into play at startup as the collected EVAP gasses are sucked in.
The throttle and pedal codes are basically tied together. So if both sensors are new then it’s a connection or grounding issue. Try cleaning the connections and add dielectric grease. Perhaps even check the grounding points on that harness.
