Emissions

P0064 — HO2S Heater Control Circuit High (Bank 2 Sensor 3)

Severity: low Safe to drive

What P0064 means

The engine control module switches a heater inside the oxygen sensor so it reaches operating temperature quickly and reads exhaust gases accurately. P0064 sets when the heater control circuit for bank 2, sensor 3 shows higher voltage than expected. Common causes are a wire shorted to battery voltage, a failed sensor heater, or less often a fault inside the control module.

Symptoms

  • Check Engine light is on
  • Slightly rough idle after a cold start
  • Higher fuel consumption
  • Failed emissions test
  • Often no noticeable change in how the engine runs

Possible causes

  1. Failed oxygen sensor heater (bank 2, sensor 3)
  2. Heater control wire shorted to battery voltage
  3. Damaged wiring or corroded connector pins
  4. Blown fuse or faulty relay in the heater circuit
  5. Faulty ECM (rare)

How to diagnose

  1. Read the codes and freeze frame data, clear the code and see if it returns.
  2. Locate bank 2 sensor 3 using a diagram for your vehicle.
  3. Inspect the sensor wiring and connector for chafing, melting or corrosion.
  4. Check the heater fuse and relay.
  5. Measure the sensor heater resistance and compare it to the factory specification.
  6. Use a multimeter to check for voltage on the heater control wire when the ECM should not be supplying it.
  7. Test the harness between the sensor and ECM for a short to power.
  8. If wiring and power are good, test the ECM heater driver.

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
  • Replace or reprogram the ECM (rare)

Questions and answers

What does P0064 mean?

It means the ECM sees abnormally high voltage in the heater control circuit of the bank 2, sensor 3 oxygen sensor. The cause is usually wiring or the sensor itself.

Can I drive with code P0064?

Yes, usually. It is not a critical fault, but it can raise fuel use and cause an emissions test failure, so get it diagnosed soon.

Do I need to replace the sensor for P0064?

Not always. Check the wiring, connector, fuse and relay first, and replace the sensor if its heater resistance is out of spec.

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.