Emissions

P0063 — O2 Sensor Heater Control Circuit Low (Bank 2, Sensor 3)

Severity: low Safe to drive

What P0063 means

The engine control module monitors the heater circuit of the Bank 2, Sensor 3 oxygen sensor, which is usually located after the catalytic converter. The heater brings the sensor up to operating temperature quickly so it can read exhaust oxygen accurately. P0063 sets when the heater control circuit voltage is lower than expected, due to an open, a short to ground, a failed heater element or a faulty driver in the ECM.

Symptoms

  • Check engine light on
  • Slightly higher fuel consumption on cold starts
  • Delayed closed-loop operation
  • Failed emissions test
  • Occasionally unstable idle

Possible causes

  1. Failed heater element in the Bank 2 Sensor 3 oxygen sensor
  2. Open or high resistance in the heater wiring or connectors
  3. Poor connection or ground problem
  4. Heater control wire shorted to ground
  5. Blown fuse or faulty relay in the heater circuit (if equipped)
  6. Faulty heater driver in the ECM (uncommon)

How to diagnose

  1. Scan for codes and freeze frame data, and note any other oxygen sensor codes
  2. Inspect the wiring and connector at Bank 2 Sensor 3 for chafing, heat damage and corrosion
  3. Check the heater fuse and relay if the circuit has them
  4. Measure the sensor heater resistance and compare it with the spec for the vehicle
  5. Check for power and the control signal at the connector with the ignition on
  6. Test the control wire for opens and shorts to ground
  7. Look for exhaust leaks near the sensor
  8. If wiring checks out, suspect the ECM only after ruling out everything else

Common fixes

  • Replace the Bank 2 Sensor 3 oxygen sensor
  • Repair the wiring or connector in the heater circuit
  • Replace the blown fuse or faulty relay
  • Reprogram or replace the ECM if the driver is confirmed faulty

Questions and answers

What does P0063 mean?

It means low voltage in the heater control circuit of the Bank 2, Sensor 3 oxygen sensor. The sensor itself or its wiring is the most common culprit.

Can I drive with P0063?

Usually yes, for a short time. The engine typically runs normally, but emissions and fuel use may increase, so repair it soon.

How do I fix P0063?

Check the wiring, connector and fuse first, then measure the heater resistance. Replacing the oxygen sensor is the most common fix.

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.