P0064 – HO2S Heater Control Circuit High (Bank 1 Sensor 3)
The P0064 diagnostic trouble code indicates that the Engine Control Module (ECM) has detected a high voltage condition in the heater control circuit of the heated oxygen sensor (HO2S) located at Bank 1 Sensor 3.
The heater element inside the oxygen sensor is designed to warm the sensor quickly after engine startup. If the ECM detects voltage higher than the expected range in the heater control circuit, it stores the P0064 code and illuminates the Check Engine Light.
Common Symptoms
- Check Engine Light ON
- Delayed oxygen sensor operation
- Slight increase in fuel consumption
- Usually no significant drivability problems
Common Causes
- Faulty heated oxygen sensor (HO2S)
- Short to battery voltage in the heater circuit
- Damaged wiring or connector
- Faulty heater control circuit
- Rarely, a faulty ECM
Basic Diagnosis
Inspect the oxygen sensor wiring and connector for damage, check the heater fuse, verify power and ground, test for a short to battery voltage, and measure the heater resistance with a multimeter. Replace the oxygen sensor if it does not meet the manufacturer's specifications.
Diagnostic Note: Bank 1 Sensor 3 is not used on all vehicles. Oxygen sensor locations, wiring colors, and heater circuit specifications vary by manufacturer and exhaust system design. Always refer to the factory service manual and wiring diagram before testing.