Pcm Code P043 - Front Oxygen Sensor Rich Signal: Action

PCM turns on SERVICE ENGINE SOON light. PCM turns on canister purge solenoid if Code P045 is also set.

NOTE: Test numbers refer to numbers on diagnostic chart.

If PCM Code P017 is present, diagnose this code first since an oxygen sensor not ready can cause other emission related problems.
If oxygen sensor is operating correctly, voltage should fluctuate at less than 0.6 volt. A rich sensor condition will cause voltage to remain at greater than 0.6 volt.
If voltage measured is less than one volt, PCM and circuit No. 1589 are okay. See CHART 8 under POWERTRAIN CHARTS.

Fig 1: PCM Code P043 Schematic - Front O2 Sensor Rich Signal

Courtesy of GENERAL MOTORS CORP.

Fig 2: PCM Code P043 Flow Chart - Front O2 Sensor Rich Signal

Courtesy of GENERAL MOTORS CORP.