Action Taken
ECM turns on "Engine Control System Fault" telltale. ECM enables canister purge. ECM uses right oxygen sensor information for fuel control unless codes EO13, EO44, or EO45 are set.
NOTE:
The following step numbers refer to circled numbers on diagnostic chart. See Fig 1
. For circuit identification, see Figure
.
- With the oxygen sensor disconnected, parameter ED32 should remain at reference voltage (0.38 to 0.63 volts).
- Checking for sensor circuitry able to record lean readings.
- The ECM compares oxygen sensor signal voltage received on circuit 412 to the ground voltage on circuit 413. If the ground voltage on circuit 413 is not engine ground (battery negative), the oxygen sensor can appear falsely high or low. With the engine running, use a voltmeter to measure voltage from the oxygen sensor pin A to the ECM terminal B6. If the voltage is greater than -0.05 to +0.05 volts, repair poor ground on CKT 413 between ECM terminal B6 and engine ground.