Code P044, Rear Oxygen Sensor Signal Lean: Action

WARNING: This page is about a different car, the 1995 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.

PCM turns on MIL. PCM turns on canister purge solenoid if Code P042 is also set.

NOTE: Test numbers refer to numbers on diagnostic chart.

If Code P013 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 greater than 0.3 volt. A lean sensor condition will cause voltage to remain at less than 0.3 volt.
If voltage measured is greater than 0.15 volt, PCM and circuit No. 1670 are okay.

Fig 1: Code P044 Schematic, Rear O2 Sensor Signal Lean

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code P044 Diagnostic Flow Chart, Rear O2 Sensor Signal Lean

Courtesy of GENERAL MOTORS CORP.