Question about 2005 Pontiac Grand Prix

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My car shuts off, reduced engine light power message and also the engine light is on

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  • te_irvin Sep 04, 2010

    Yes I know, it is frustrating to me. This is what happens....I am driving then this computerized message come up (reduced engine power ) and the it says the car will be disabled. I have no steering power at all. The engine light is comes up when it says engine power reduced and then it goes by itself. No start for maybe 2mins or so. I wait and then it starts back up. the guy said nothing is showed up when he test the car becasue my engine light is not only comes on when the car is about to shut off. I am updated on my oil change and just recently had mytrans fluid exchanged so I have no idea...maybe my spark plugs?

  • te_irvin Sep 04, 2010

    THANK YOU!!! I appreciate your efforts greatly. I will do that. I am so scared to drive it because of the loss of the steering power. I will let you know. It will be tomorrow because I have somewhere to be. Thanks again!!!!!!!!

  • te_irvin Sep 18, 2010

    Hi jturcotte. Just wanted to give you an update. First of all you were very helpful! I have the reduced engine power issues. Well, I got a new throttle body assembly, along with injector cleaning, fuel injection service... (because the throttle assem. was showing up as the problem) but it was still doing the same thg. after the new one was put on. So, the mechanic said I needed a new pcm...which is still under warranty (thank God!!!). I have to wait until monday now to see when GM dealer can install. But thanks again!!! I hoping that this will be the finally stop! =)

  • te_irvin Sep 18, 2010

    Hi, just wanted to say first of VERY helpful! Just to keep you updated, so that you could help someone else. Well, it showed up that my throttle body was bad. I had that replaced and the "reduced engine power" still continue. So now I need a new pcm...which so happens to be still under warranty (thank God!!!). I called the GM dealer to see when they can replace my current one. THANKS again!



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Please have the car scanned for trouble codes. Many parts stores provide free scans.

Posted on Sep 04, 2010

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  • te_irvin Sep 04, 2010

    Thanks, I did. Everything is showing up as problems?????

  • Jeff Turcotte
    Jeff Turcotte Sep 04, 2010

    Hmmm...and the engine light is on? Engine light indicates the computer has stored a trouble code. Is the light still on, or did it go out? Even if it went out, the code should still be there, as the computer keeps a record. maybe the guy that scanned your car was not trained right. Can you tell me more about the history of the problem and a typical episode of driving it?

  • Jeff Turcotte
    Jeff Turcotte Sep 04, 2010

    I've had them tell me that they can only get codes when the light is on, then I take the scanner from them and do it myself. I'm pretty sure the codes are in there. The next time you go by one of those stores, see if you can find someone that looks like they know what they are doing and ask THEM to scan for "history of codes." In the meantime, I'll do some research on how the computer decides to shut off you car (a very bad design in my opinion). It is not your spark plugs.

  • Jeff Turcotte
    Jeff Turcotte Sep 04, 2010

    New question: does your car have active fuel management? This is a feature that disables 4 of the 8 cylinders to save gas when you are driving slow. I'm assuming you have the V-8 engine.
    If you have this feature, I'd say the problem is related to that system and you may have a bad computer. Anyway, that system is way beyond anything I can help you with, as it will take an expert in that system to troubleshoot. What you can do without an expert is to get a complete tune up, including cleaning out the throttle body and injectors and hope the problem goes away--or if you can get any trouble codes,let me know. If you don't have the active fuel management, do get the tuneup. The codes associated with the reduced power message have to do with the throttle body and the throttle position sensor, which is on the throttle body.

  • Jeff Turcotte
    Jeff Turcotte Sep 18, 2010

    Thanks very much for the update and feedback. Hope they have you fixed up soon!!



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SOURCE: SES light then Reduced engine power light, loss of engine power

Hi It me Mohammad Siddiq my dear. First of all it will be wise of use to take your vehicle to a dealership or any other fully equipped w/shop. They can better tell you what the fault your vehicle has. But at the same time if your friend has the same model vehicle so you can exchange some parts with that vegicle, e.g., Mass Air Flow or TPS (Throttle Position Sensor) and can check your vehicle. These parts do not need to be programmed with scan tool. Just Simply replace these parts and switch on the ignition and wait for 01 minute, then switch off for 30 seconds and then start the engine. Now road test your vehicle, if no SES light or reduced power then there was fault with the part/s replaced. So Return those parts and now you must replace these parts with new or used ones. Anything else I may be contacted on my yahoo id Thanks. I am an auto technician and working in a GM dealership in Saudi Arabia. I am from Pakistan.

Posted on Apr 28, 2009

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SOURCE: service engine soon and reduced engine power

disconnect batt. for 30 min. then reconnect,if no problem exist the lights will go away

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SOURCE: Message ' Reduced engine performance'

sound like transmission slipping .fuel filter clogged.turbo stop woking.dirty fuel injectors.

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SOURCE: check engine light "reduced enging power" message?

hook it up to OBD 2 scan retrieve fault code and go from that point!

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SOURCE: 2005 chevy cobalt, car wont start ... check

have car scanned for trouble code some auto stores such as auto zone---advanced auto scan for free the code[s] will give u a start point towads correcting ur problem

Posted on Jan 06, 2010

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