Engine runs fine after ECU reset, poorly shorty after

[tmontague]

Originally Posted by Bluevitz-rs

Ok, just checked and there's no O2 wire on your OBD port, it's only available on Conector C Pin 16 on the ECU. It is a white wire. Pin 13 is also white, but is the knock sensor.

The reading should oscillate from .050V - .900V

So in other words, within 1V. It should swing back and forth if you hold the revs at about 2000. If it's not going all the way up and all the way down, the sensor is shot.

Mine was reading 0.100-0.550V and no code we set but my millage was getting bad and I had a rougher idle. My fuel trims where shooting up to +23% at idle. Changed the sensor and started getting 100km more per tank and the idle smoothed out a bit.

edit: for reference, low voltage is a lean reading and high voltage is a rich reading on an O2 sensor. If the sensor is only showing the ECU half way up the scale it'll think its too lean and start increasing the fuel trims. It can get to the point that it's so rich it's flooding the engine and fouling up the cat. Another indicator can be a rotten egg smell from the exhaust.

Does the primary or secondary O2 sensor tend to wear out quicker?