I'm having a similar issue with a Pontiac Montana SV6, Brought it to the shop, they said it could be a failing Oxygen sensor. The problem since went away for quite a while, but now it's back, then gone again. My gas consumption went way up, I mean at least double. When i first reported the problem to the car dealership, the fellow suggested to check the gas cap. I did, it appeared loose, so I fixed that. The engine light turned off right away. But the problem is back with a vengeance. The idling has become rough. In fact, when I started the motor in -20c temp one day, it actually backfired.
I thought that I had run out of oil because the gas consumption was so high. (excessive friction I wondered).
On another note. This vehicle is equipped with a GPS starter blocking device. I wondered if RF interference from that device could be causing the on-board computer to misunderstand signals being sent by a variety of sensors.
Would love to read comments on this.
For now though, all points to this oxygen sensor. But because the problem is intermittent, no hard faults appeared in the diagnostic.
So now I am looking at buying an engine diagnostic data logger so that if the problem re-appears, I will have a log of the hard faults required by the service station, so I can get this thing fixed on warranty.
Did you make sure that the gas cap was on tight and proper... i have had that happen before...
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service engine soon light, trac light and anti-lock light all came on at once. no warning, no problems, nothing, lights up like a Christmas tree.
What do I do?
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