Pontiac Trans Sport van, 94 - "engine" light comes on after 15 min? Gas per km is...

[120]

...now much less.? 1. It had no light before when It passed emissions Test PRIOR to have engine rebuilt (stuck valve stem; new pistons, timing chain, sparks, cables, wires, dist. cap, rotor, oil pan, gaskets, ETC).

2. Muffler has hole in it. Hole WAS ion there before the engine repair.

3. Gasoline consumption is greater now.

I took to "magicians" that repair engine and they told me "the scanner shows O2 sensor" but did not provide a code reference (I think they just made it up, because they do not know enough electronics for this).

Any ideas?

[Frankie]

Just swing into an auto parts store and ask them to scan it for you. Most will do this at no charge and even give you a print out of the results.

[joemong]

go get a second opinion.

[Tom]

If they are actually correct an o2 sensor can indeed ruin fuel mileage. If the o2 sensor is reading a mixture of to lean or to heavy it can ultimatly change the way the vehicle runs, i had this happen in my caviler and i chased the problem changing everything from the plugs and wires to other common problems, and it ended up being an o2 sensor, it was a pretty cheap fix and thats all it ended up being. the code that mine threw was emissions tracking error. which indeed was the o2 sensor.