TEST
ACTION
APPLICABILITY
1
NOTE: If one of the O2 Sensors Signal or Return circuits are shorted to
ground, the DRBIII
t will display all O2 Sensor voltage readings low. The O2
Sensor that is shorted to ground will display a voltage reading near or at 0
volts.
NOTE: It is important to perform the diagnostics on the O2 Sensor that set
the DTC.
NOTE: After the repairs have been made, verify proper O2 Sensor operation.
If all the O2 Sensor voltage readings have not returned to normal, follow the
diagnostic procedure for the remaining O2 Sensors.
Start the engine.
Allow the engine to reach normal operating temperature.
With the DRBIII
t, read the O2 Sensor voltage.
Is the voltage below 2.52 volts?
All
Yes
→ Go To 2
No
→ Refer to the INTERMITTENT CONDITION symptom in the
Driveability category.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
2
Turn the ignition off.
Disconnect the O2 Sensor harness connector.
Ignition on, engine not running.
With the DRBIII
t, monitor the O2 Sensor voltage.
Is the O2 Sensor voltage above 4.8 volts?
All
Yes
→ Go To 3
No
→ Go To 5
3
Turn the ignition off.
Disconnect the O2 Sensor harness connector.
Ignition on, engine not running.
Measure the voltage on the O2 Return circuit in the O2 Sensor harness connector.
Is the voltage at 2.5 volts?
All
Yes
→ Replace the O2 Sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No
→ Go To 4
4
Turn the ignition off.
Disconnect the O2 Sensor harness connector.
Disconnect the PCM harness connector.
Measure the resistance between ground and the O2 Return circuit in the O2 Sensor
harness connector.
Is the resistance below 100 ohms?
All
Yes
→ Repair the short to ground in the O2 Return circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No
→ NOTE: Before continuing, check the PCM harness connector
terminals for corrosion, damage, or terminal push out. Repair as
necessary. Replace and program the Powertrain Control Module
in accordance with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
318
DRIVEABILITY - NGC
P0131-O2 SENSOR 1/1 VOLTAGE LOW —
Continued