O2 Sensor 1/2 Below Threshold

P0137 - O2 SENSOR 1/2 BELOW THRESHOLD

P0137 - O2 Sensor 1/2 Below Threshold:

WHEN MONITORED
Start and drive vehicle greater than 32 km/h (20 MPH) and less than 89 km/h (55 MPH). Throttle open for a minimum 120 seconds. Coolant Temp greater than 70° C (158° F) and Catalytic Converter Temperature greater than 600° C (1112° F).

SET CONDITION
The O2 sensor voltage switches only 11 times or less from rich to lean within 20 seconds during monitoring. Two Trip Fault.

POSSIBLE CAUSES
- Exhaust leak
- O2 sensor signal circuit
- O2 sensor ground circuit
- O2 sensor


DIAGNOSTIC TEST




1. CHECK FOR CURRENT DTC

Turn the ignition on.
With the DRB III(R), read PCM DTCs.

Q: Is this DTC present?

YES: For complete diagnosis of this DTC, refer to (P0137) O2 SENSOR 2/2 ABOVE THRESHOLD.

NO: Go To 2

2. INTERMITTENT WIRING AND CONNECTORS

The conditions necessary to set this DTC are not present at this time.

NOTE:
- Check connectors - Clean/repair as necessary. Poor pin to terminal connections can set DTCs. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors specific to this DTC. Wiggle the wires while checking for shorts and open circuits.
- Check for any Technical Service Bulletins that may apply.

Q: Were there any problems found?

YES: Repair as necessary.
Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2

NO: The condition that caused this DTC to set is currently not present. Inspect the related wiring harness for a possible intermittent condition.