O2 Sensor Heater Control Circuit High (Bank 2 Sensor 3)
The P0064 code indicates that the powertrain control module (PCM) has detected a high voltage condition in the heater control circuit for the oxygen sensor located after the catalytic converter on bank 2 (the side of the engine without cylinder #1). This sensor (sensor 3) monitors catalyst efficiency. The heater circuit is essential for quick sensor warm-up during cold starts. A high voltage reading suggests a short to power, a faulty sensor, or a wiring issue.
01. Most Common Causes
- Shorted or damaged wiring in the heater circuit
- Faulty oxygen sensor (Bank 2 Sensor 3)
- Blown fuse or relay for the O2 sensor heater
- Corroded or loose connector at the sensor
- PCM failure (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Failed emissions test
- Possible poor fuel economy
- Rough idle or hesitation (less common)
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for other codes.
Step 2: Visually inspect the wiring and connector for Bank 2 Sensor 3 for damage, corrosion, or shorts.
Step 3: Test the heater circuit voltage at the sensor connector (should be battery voltage with key on).
Step 4: Measure resistance of the heater element (typically 2-10 ohms). If out of range, replace the sensor.
Step 5: Check fuses and relays related to the O2 sensor heater circuit.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but the vehicle may fail an emissions test and fuel economy could suffer. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
Typically $150-$400, including parts (O2 sensor $50-$150) and labor ($100-$250).