Car in limp mode, codes p0106 and p0651

2009 CHEVROLET COBALT

186,000 MILES • 2.2L • 4 CYL • 2WD • AUTOMATIC

ROGERBA

MEMBER
1 POST

Car lost power, limp mode, check engine light comes on, tachometer in dash quits working, no throttle pedal, runs rough. Scan car and had a p0106 and p0651. Could this simply be the MAP sensor?

Jun 11, 2019 at 1:09 PM

KASEKENNY

✓Experienced Mechanic
18,907 POSTS

Hi Rogerba,

It could be a MAP sensor but looking at the codes and the symptoms you have, I suspect you have a 5 volt reference issue. This could be a MAP that shorted and took down your reference signal but either way, I would do some checking on this circuit. The reference circuit does not effect just one system. The P0651 is your 5 volt reference 2 circuit. This is shared by the throttle position which is probably why you lost throttle response. The crank uses this as well which is why you lost the tachometer which forced the limp in mode. The running rough and lose of power was due to the MAP. The PCM uses MAP, MAF, and TP to control air/fuel ratio.

Long story short, I would run through the diagrams just to make sure you don't have a short in your 5 volt reference.

I attached the diagrams for both codes. Let me know what you find. Thanks

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