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2006 Pontiac Grand Prix lost power

Hello there, first time poster here at the forum, I’d like to know that my car is not about to die on me. I have a 2006 Pontiac Grand Prix, it’s got about 193,000 miles on it, automatic transmission. All the miles are highway miles from the interstate, and I keep it well-maintained

Earlier today I got on the interstate to drive to work, and as I am on the interstate I got my car up to 75 miles an hour which is usually my speed on the interstate, all of a sudden I could feel the engine beginning to slow down and as I look down I saw the check engine light blinking on and off.

Now suitably freaked out, and worried that my engine is about to be in 1000 pieces when I get out of the car, I pull over to the shoulder popped the hood look in and I see nothing is wrong. Engine looks fine I smell no smoke or no steam or anything else, it all looks the way it should. I got back in the car turned over the motor which, turned over just fine, got back onto the interstate and made the drive to Knoxville (30 miles) in the car handled perfectly well. It drove just the way it always did, I didn’t feel any shaking are generating I didn’t hear any misfires or didn’t hear the transmission struggling to shift gears. It just drove the way that it should. Which is good for me

Anyway I had a few minutes to kill before my shift at work started so I quickly checked and I found out what it was in is limp mode, which happens to a car if the transmission is about to go down and it’s getting you home. But I think it’s just a bit of a fluke because once I turned off the motor and turn it back on the engine light turned off and it let me Drive normally.

I need to know, should I be concerned about this, should I take it to a mechanic I don’t know what to do. The only problem is I’m saving up my money for a big trip in August and I just got this car paid off. And I don’t want to see my entire vacation fund get obliterated because of this. Any advice you guys can give I would be greatly appreciative.

When a Check Engine flashes, it indicates a major misfire is occurring.

Who knows? Maybe the fuel pump is weak?

Driving at 75 MPH requires that the fuel pump deliver proper pressure/volume of fuel to the engine. Otherwise the engine can start to run lean causing misfires.

But you don’t want that Check Engine to flash. Because each time it does, it indicates damage to the engine and/or catalytic converter may be occurring.


It could be a lot of things. But the longer you wait the more it will cost you in the end.

I appreciate the advice, but there is one thing that I am confused about. If I turned the car completely off turn the engine off and everything, turned it back on again and it was working perfectly no flashing of the check engine light or anything else, what could that mean

It means the misfire was no longer occurring. So the the Check Engine light shut off.

Pay attention if the misfire/Check Engine light only occurs at higher speeds. If it does, I’d have the fuel pump tested for both pressure and volume.


"… I don’t know what to do."

I’ll bet you love driving that Grand Prix. I have one and I’m looking for another one. They’re awesome.

I’d get the OBD2 (Onboard Diagnostic 2nd Version) DTCs (Diagnostic Trouble Codes) read right away (codes can clear if too much time evolves). Most “chain” auto parts will do it for free. A more sophisticated engine analyzer, operated by a real technician is better. Anyhow, post the code(s) here and we will advise.

There are pro mechanics here that you are talking with and there’s guys like me, too.

Please come back.

Thank you for the information. I spoke to my father he knows more about cars than I do. And he told me to just drive it for a couple of days and if it happened again then take it in to be checked out. He seemed to think it might’ve just been a misfire, and because the check engine light is off I can’t have it looked at. Anyway I drove home tonight, and I was able to get the car up to 70 with no trouble and it drove just fine.

Your father is wrong. The codes will be stored in the memory, but not for long. That is why you should have the codes read ASAP. The codes stored could point to a major problem and you may be able to avoid an expensive repair bill if it’s fixed before more damage is done.

Without the codes there are too many things that could have caused the computer to put the car into limp mode.

You did not mention…so I’ll add…you also should have checked the oil level before you restarted the engine.


As long as the engine light is lit then the codes should still be there.

In the original post he said

"But I think it's just a bit of a fluke because once I turned off the motor and turn it back on the engine light turned off and it let me Drive normally".

Still the code will be in the History, but not for long.


well I had my car serviced today. They get an oil change, checked all my fluids. And so far my car is still running like a top

This might have been caused by an intermittent poor electrical connection. It could be very difficult to track down, or it could as simple as loose mounting screws on the ECM (engine computer).

If that happened to my Corolla, even if it cleared up on its own, first thing I’d do is read out all the diagnostic codes. That’s the quickest way to figuring out what’s happening.

If I had to guess without the codes … hmmmm… well, I’d be most suspicious of the fuel pump, fuel filter, a bit of bad gas, air filter, fuel pressure regulator, and evap system.