Pcm Code E44, Oxygen (O2) Sensor Lean Exhaust Signal: Action

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

1. With O2 sensor disconnected, parameter P.1.4 should remain at reference voltage (.38-.63 volt).
2. Checks ability of sensor circuitry to record rich readings. DVOM set on volts will provide a very small current source to drive circuit No. 412 to greater than .64 volt (rich). Similar results may be obtained by placing one finger on O2 sensor circuit No. 412 harness terminal and another finger on positive battery terminal.
3. PCM compares O2 sensor signal voltage received on circuit No. 412 to ground voltage on circuit No. 413. If PCM does not have a good ground to engine on circuit No. 413, O2 sensor reading can falsely appear high or low. With engine running, use a voltmeter to measure voltage from O2 sensor at exhaust manifold to PCM terminal E15. 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 E15 and ground at front of engine (right rear of cylinder head).