OBD Guide

P0138

O2 Sensor Circuit High Voltage Bank 1 Sensor 2

P0138 is an OBD-II diagnostic trouble code meaning: O2 Sensor Circuit High Voltage Bank 1 Sensor 2. Common causes: oxygen sensor malfunction (bank 1 sensor 2), damage to the sensor wiring harness. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Increased fuel consumption
  • Unstable engine operation
  • Check Engine Light Is On
  • Reduced catalytic converter efficiency

Causes

  • Oxygen sensor malfunction (Bank 1 Sensor 2)
  • Damage to the sensor wiring harness
  • Short circuit in the sensor circuit
  • Exhaust leaks
  • Fuel system problems (mixture too rich)

How to Fix

  1. Check the sensor wiring harness for damage.
  2. Check sensor connections and connectors
  3. Check the voltage in the sensor circuit
  4. Replace the oxygen sensor if necessary
  5. Check the exhaust system for leaks

Related codes

Error P0138 by Vehicle Brand

FAQ

What does the P0138 code mean?

P0138 is an OBD-II diagnostic trouble code that indicates: O2 Sensor Circuit High Voltage Bank 1 Sensor 2

What causes a P0138 error code?

The most common causes of P0138 include: Oxygen sensor malfunction (Bank 1 Sensor 2); Damage to the sensor wiring harness; Short circuit in the sensor circuit; Exhaust leaks.

How do I fix a P0138 diagnostic trouble code?

To fix P0138: Check the sensor wiring harness for damage.. Check sensor connections and connectors. Check the voltage in the sensor circuit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0138?

Limited driving only, diagnose soon

How much does it cost to fix P0138?

The estimated repair cost for P0138 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat