Pcm Code E043, Left Oxygen (O2) Sensor Rich Signal: Action

PCM turns on SERVICE ENGINE SOON light. PCM turns on canister purge solenoid.

1. With O2 sensor disconnected, parameter ED32 should remain at reference voltage (.38-.63 volt).
2. Checks O2 sensor circuitry ability to record lean readings.
3. PCM compares O2 sensor signal voltage received on circuit No. 1589 to ground voltage on circuit No. 413. If PCM does not have a good ground to engine on circuit No. 413, O2 sensor can appear falsely high or low. With engine running, use a voltmeter to measure voltage between O2 sensor at exhaust manifold and PCM terminal B6. If voltage is -.05 to +.05 volt, ground is okay. If voltage is less than -.05 volt or greater than +.05 volt, repair poor ground on circuit No. 413 between PCM terminal B6 and ground at front of engine on right cylinder head.