O2 Sensor 1/2 Circuit Open

P0138 - O2 SENSOR 1/2 CIRCUIT OPEN





When Monitored and Set Condition

- When Monitored: With the engine running between 1000 and 2000 RPM, engine load between 15% to 50%, closed loop mode, the three way catalytic converter temperature is greater than 380° C (716° F), and the O2 sensor heater must be ON for at least 220 seconds to enable the signal inactive portion of the test.
- Set Condition: O2 Sensor voltage is less than 0.15 volt for approximately 5 seconds. Signal stays at center: The O2 Sensor voltage stays between 0.4 and 0.6 volt for more than approximately 15 seconds after the O2 Sensor heater has been ON for at least 220 seconds.







Diagnostic Test

1. CHECK FOR CURRENT DTC





Turn the ignition on.

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

Is this DTC present?

Yes

- For complete diagnosis of this DTC, refer to (P0131) O2 SENSOR 1/1 CIRCUIT LOW. P0131

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.

NOTE: Check for any Technical Service Bulletins that may apply.

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.