Late Production (NGC)

Test 1 - 4:

Test 5 - 8:

SYMPTOM
P0137-O2 SENSOR 1/2 VOLTAGE LOW

TEST NOTE
This symptom is diagnosed using the test P0131-O2 SENSOR 1/1 VOLTAGE LOW.

WHEN MONITORED
Engine Running.

SET CONDITION
The oxygen sensor signal voltage is below 2.4O2 volts for 9 seconds. Two trip Fault.

POSSIBLE CAUSES
- O2 sensor below 2.52 volts
- O2 sensor
- O2 return circuit shorted to ground
- O2 signal circuit shorted to ground
- O2 signal circuit shorted to O2 return circuit
- O2 signal shorted to heater ground circuit
- PCM return circuit
- PCM signal circuit