[Dr Scientifico]

I recently bought my mother's 2.4 L 2009 Pontiac G6 with ~135,000 miles on. As far as I know, the only issues with it before this past weekend were the tire pressure sensors (I think two of them had their batteries die) and the traction control (which would turn off every once in a while but would turn back on; from Googling my issue, I think this is pretty common?).

Since getting the car, I've only put on a hundred miles or so without issue. That is, until this past Sunday, when I got a mile or two from my house. At that point, the traction control light came on, so I slowed down. The light went off, so I accelerated back to speed, though I noticed it was a bit hesitant to do so. The light came back on, I slowed down again, and at this time it became apparent that the car was losing power, so I pulled over and turned the car off. When I turned the car back on, the TC warning light was still on, but now there was the CEL, and the engine was shaking like an unbalanced washing machine while in idle. When I put it in drive, I managed to get maybe a block down the road before the engine died.

At this point, I had the car towed home so I could borrow an OBD reader to scan for codes. I tried doing that today, and the reader was not able to communicate with the computer no matter what I did. I also had some new issues: there’s a message of "ERROR" alternating with the total odometer reading and the gas gauge bounces up and down from a quarter tank to empty (though the car starts). I think the infotainment center also says that power steering is off, but there's no corresponding light on the dashboard.

So that's where I am at: I've got a G6 with a CEL, a fuel gauge that goes up and down, and an engine that shakes very roughly at idle, but I can't get any codes to diagnose what might be wrong. I have tried disconnecting the battery for a few minutes, but that didn't seem to do much. I do have some Iso-Heet on hand in case this could be the result of some water vapor in the gas tank, but I'm not sure that would be triggering so many issues at once. Any thoughts of where to proceed next?

 

[Dan Osier]

Have you tried switching off your traction control ? My traction control is NEVER turned on. I have no faith in these systems. To me they are like electric parking brakes, automatic climate control, ETC. I do like anti-lockup brakes though as they are pretty much sorted out by now. Americans are not good at electronics anymore unless they are making things for NASA. ( Board of Directors say "use Chinese capacitors" )

Clue to GM....if nobody wants to buy your used cars, nobody wants to buy your new cars.

 

[Dr Scientifico]

Have you tried switching off your traction control ? My traction control is NEVER turned on. I have no faith in these systems. To me they are like electric parking brakes, automatic climate control, ETC. I do like anti-lockup brakes though as they are pretty much sorted out by now. Americans are not good at electronics anymore unless they are making things for NASA. ( Board of Directors say "use Chinese capacitors" )

Clue to GM....if nobody wants to buy your used cars, nobody wants to buy your new cars.

When I first pulled over, I tried turning the traction control back on (since it turning off is what started this misadventure) and off, but it never changed anything that I could tell. Given my mother acted like it turned itself off at random times before this without issue, I suspect the traction control really doesn't provide much to the driver anyway.

 

[Dr Scientifico]

I recently bought my mother's 2.4 L 2009 Pontiac G6 with ~135,000 miles on. As far as I know, the only issues with it before this past weekend were the tire pressure sensors (I think two of them had their batteries die) and the traction control (which would turn off every once in a while but would turn back on; from Googling my issue, I think this is pretty common?).

Since getting the car, I've only put on a hundred miles or so without issue. That is, until this past Sunday, when I got a mile or two from my house. At that point, the traction control light came on, so I slowed down. The light went off, so I accelerated back to speed, though I noticed it was a bit hesitant to do so. The light came back on, I slowed down again, and at this time it became apparent that the car was losing power, so I pulled over and turned the car off. When I turned the car back on, the TC warning light was still on, but now there was the CEL, and the engine was shaking like an unbalanced washing machine while in idle. When I put it in drive, I managed to get maybe a block down the road before the engine died.

At this point, I had the car towed home so I could borrow an OBD reader to scan for codes. I tried doing that today, and the reader was not able to communicate with the computer no matter what I did. I also had some new issues: there’s a message of "ERROR" alternating with the total odometer reading and the gas gauge bounces up and down from a quarter tank to empty (though the car starts). I think the infotainment center also says that power steering is off, but there's no corresponding light on the dashboard.

View attachment 18382

So that's where I am at: I've got a G6 with a CEL, a fuel gauge that goes up and down, and an engine that shakes very roughly at idle, but I can't get any codes to diagnose what might be wrong. I have tried disconnecting the battery for a few minutes, but that didn't seem to do much. I do have some Iso-Heet on hand in case this could be the result of some water vapor in the gas tank, but I'm not sure that would be triggering so many issues at once. Any thoughts of where to proceed next?

Bit of an update to this: I took my multimeter out this morning to measure the terminal voltage of the battery since some of the issues could be related to a bad battery, and I only got about 11.9 V. Given that it is a little over 3 years old AND apparently came off her old Ford Escape, I'm thinking that's the source of a lot of my problems.

 

[Dr Scientifico]

Another update: after taking the battery out and charging it for a few hours, I was able to get my OBD-II reader to communicate. I now have three error codes (and the charged battery appears to have cleared out some of the issues like the fluctuating fuel gauge needle and the ERROR message on the odometer):

P0107 - Manifold Absolute Pressure/Barometric Pressure Circuit Low
P0202 - Injector Circuit/Open - Cylinder 2
P0204 - Injector Circuit/Open - Cylinder 4

Once it gets a bit warmer, I'll go in and check out the injectors and various circuitry, but that's where I am now.

 

[boomer]

Most auto parts shops will test the battery for free. May be worth giving that a go. Equally for the sake of the 100 or so dollars it may be worth just replacing it if you suspect it may be an issue. If you are happy you have a good battery and charge, I would clear the codes and see what comes back. Anything persistent is likely to be a problem.

The traction control system relies on engine control (rev limiting etc). A number of engine error codes will also set the TC disabled indicator. I would focus on any residual engine codes rather than the TC light.

Hope you get it fixed.

 

[Dr Scientifico]

Most auto parts shops will test the battery for free. May be worth giving that a go. Equally for the sake of the 100 or so dollars it may be worth just replacing it if you suspect it may be an issue. If you are happy you have a good battery and charge, I would clear the codes and see what comes back. Anything persistent is likely to be a problem.

The traction control system relies on engine control (rev limiting etc). A number of engine error codes will also set the TC disabled indicator. I would focus on any residual engine codes rather than the TC light.

Hope you get it fixed.

I'm definitely going to get the battery checked out. It does charge, so a few of my more mechanically inclined friends have suggested that it is the alternator. I plan on throwing the battery back in after fully charging it to see if I notice any weirdness with the alternator using my multimeter, then taking one or both to a shop for testing.

 

[Dr Scientifico]

Just a quick update: Since I had several friends who said it could be an alternator issue, I fully charged up the battery on my charger (it was right around 12.5 V when I measured it), put it in the car, and found the following:

12.15 V when in the car, but with the car off
12.06 V when in the car with the ignition on
11.81 V (!) when in the car with the ignition on and the headlights on
~14.3 V when in the car with the engine running

So, I don't think the alternator is the issue; I'm pretty sure the battery is shot.

 

[JTDCO]

Hello, I have a 2008 G6, I've had both problems. does it have a 6 or 4 cylinder? if it is a 4 and if you remove the plastic cover on the engine. Standing in front of cat the left side of the engine are to sensors. Check those I replaced mine and it corrected the shaking and idle problems. This is the sensor image i attached. The traction control light was for me the brake sensor. Behind the brake pedal. Its has a fork light prongs. One of the forks broke and caused my tail lights, cruise control and T/C not to work. Check that out.

 

[Dr Scientifico]

Hello, I have a 2008 G6, I've had both problems. does it have a 6 or 4 cylinder? if it is a 4 and if you remove the plastic cover on the engine. Standing in front of cat the left side of the engine are to sensors. Check those I replaced mine and it corrected the shaking and idle problems. This is the sensor image i attached. The traction control light was for me the brake sensor. Behind the brake pedal. Its has a fork light prongs. One of the forks broke and caused my tail lights, cruise control and T/C not to work. Check that out.

I'm starting to think at least my major issues are related to a sensor of some sort, so when I get under that plastic cover I'll be sure to check those out.

 

[Dr Scientifico]

So given the voltage measurements of my old battery, I went in and had it tested; AutoZone said it was just fine. Still, it is a 3+ year old battery that originally came off a Ford Escape and was obviously not supplying the right voltage to everything (hence my weird fuel gauge and odometer issues), so went ahead and replaced it. Unfortunately, that did not resolve my issue. I still have P0107, P0202, and P0204 codes being sent out (though only the P0107 code was listed as Current, Pending, AND Permanent). I guess I'll start testing connections and cleaning sensors; I also bought some Seafoam just in case.