Emissions

P0167 — O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 3)

Severity: low Safe to drive

What P0167 means

The engine control unit detected a problem in the heater circuit of the oxygen sensor on Bank 2 in position 3, usually downstream of the main catalytic converter. The heater brings the sensor up to operating temperature quickly so it can read exhaust oxygen accurately without waiting for the exhaust to warm up. The ECU monitors the heater's current and voltage and sets this code when they fall outside the expected range.

Symptoms

  • Check engine light on
  • Slightly higher fuel consumption
  • Unstable idle after a cold start
  • Failed emissions inspection
  • Often no other noticeable symptoms

Possible causes

  1. Burned-out heater element inside the sensor
  2. Open or shorted wiring in the sensor harness
  3. Blown fuse or missing power to the heater circuit
  4. Corroded or loose sensor connector
  5. Wire insulation damaged by contact with hot exhaust parts
  6. Rarely, a failed heater driver in the ECU

How to diagnose

  1. Read all codes and freeze frame data and look for other oxygen sensor codes
  2. Confirm which physical sensor is Bank 2 Sensor 3 using the engine's service information
  3. Inspect the harness and connector for melted insulation, chafing, corrosion or water
  4. Check the fuse and relay that power the oxygen sensor heaters
  5. Measure the heater resistance at the sensor pins and compare with specification
  6. Check for power and the control signal at the connector with the ignition on
  7. Test the wires back to the ECU for opens and shorts to ground or power
  8. Suspect the ECU only after everything else checks out

Common fixes

  • Replace the Bank 2 Sensor 3 oxygen sensor
  • Repair the wiring harness or replace the damaged connector
  • Replace the blown fuse and find what caused it
  • Repair or replace the ECU (rare)

P0167 on different brands

Ford · manuals
Ford may show this as P0167:01, meaning the Bank 2 O2 sensor heater circuit; the extended code reports the monitor condition that was detected, not a confirmed failed part.

Questions and answers

Can I drive with a P0167 code?

Usually yes, the car will run normally. The light will stay on though, and it could hide new problems, so don't put the repair off for long.

What does Bank 2 Sensor 3 mean?

Bank 2 is the side of the engine that does not contain cylinder 1. Sensor 3 is located after the catalytic converter, further down the exhaust. Check your engine's service information for the exact location.

Do I need to replace the sensor right away?

No. First check the fuse, wiring and connector, and measure the heater resistance. Replace the sensor only if the heater itself has failed.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.