Error code

OBD2 P0138

OBD2P0138
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

O2 Sensor Circuit High Voltage.

Severity

moderateCan drive, but should address the issue soon as it affects emissions.

Summary

P0138 indicates high voltage in the heated oxygen sensor circuit for Bank 1 Sensor 2, which is located after the catalytic converter.

Common Causes

  • Faulty heated oxygen sensor (HO2S)
  • Wiring or connector damage leading to a short circuit
  • Corrosion in the wiring harness

Diagnosis

  1. Check fuses and wiring for any obvious damage or corrosion.
  2. Inspect the oxygen sensors for physical damage.
  3. Verify proper seating of connectors and check for bent pins.
  4. Use a multimeter to test continuity in the sensor circuit.
  5. Replace the sensor if internal resistance is outside normal range.

Fixes

  • Replace the faulty heated oxygen sensor (HO2S).

FAQ

What does P0138 mean?

P0138 indicates high voltage in the heated oxygen sensor circuit for Bank 1 Sensor 2, which is used to monitor catalytic converter performance.

How do I fix P0138?

Fixing P0138 typically involves checking and repairing wiring issues or replacing a faulty oxygen sensor.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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