Q: 2006 Pontiac Grand Prix GT reduced engine power.

asked by on

I have a 2006 Pontiac Grand Prix GT. It's got the 3.8L 3800 Series III supercharged engine. The car overheated because of a cracked elbow pipe, blew gaskets and quit completely. After two years, I have it running again (I didn't have the time to repair it). Car sat for two years with the engine in the garage and the body outside. Now that it's fixed, car still won't go past 3,500 RPM's when I floor it in park. Car gets to 45 MPH and shows "Reduced Engine Power" then dies completely. Car idols at 1500 RPM's instead of 500, and will "gas itself" when stopped and in Drive. It will rev itself up between 1500 and 1900 RPM's and misses and shakes noticibly. I plugged into a computer and it showed codes for supercharger bypass valve, wheel sensors and ignition plate. Everything is new on it from pistons and gaskets and coil packs and spark plugs. Heard it might be throttle body. Bypass valve was replaced as well. ABS light, traction control and check engine light are on. Any ideas? Automatic not manual

My car has 147000 miles.
My car has a manual transmission.

Hey there. The reduced power light typically indicates a fairly serious problem with the throttle system. When this light illuminates the vehicle will often go into a “safe mode”, which will severely limit the speed of the car and in some cases will render the vehicle un-drivable. It’s always best to have a professional mechanic complete a reduced power light inspection to isolate the source of your issue. In regards to the other warning lights, it appears that this Grand Prix has multiple issues going on, so you might want to have the mechanic download those specific codes and help you diagnose the root source of those as well. In many cases, the code that might indicate a part failure is actually caused by a bad sensor or electrical harness.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. 2006 Pontiac Grand Prix GT reduced engine power.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: No reverse, car drives in neutral and drive

You may have a shifter cable problem with the cable ends. The plastic cable end bushing deteriorate and fall apart causing this problem and may require the shift cable to be replaced. Check cable end where it connects to transmission...

Q: Q: My car is overheating

I have never heard of a fail proof thermostat. If your coolant tank has a leak then it may be getting low on coolant. A leaking coolant tank that is unable to hold pressure can also cause the temperature to...

Q: My secondary air system, a/c refrigerant, erg flow & heated catalyst is not supported through my diagnosis. Have any suggestions?

Engine coolant is not normally added to a vehicle's cooling system as that system is well sealed and uses a recovery tank. The only reason you would have to add coolant is if there is a leak. You should, of...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...