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 of the oxygen sensor located downstream of the catalytic converter on Bank 2 (the side of the engine not containing cylinder #1). This sensor (Sensor 3) monitors catalyst efficiency. The heater circuit is essential for quick sensor warm-up to reduce emissions. A high voltage reading suggests a short to power, high resistance, or a faulty sensor.
1. Most Common Causes
- Faulty oxygen sensor (Bank 2 Sensor 3)
- Short to battery voltage in heater circuit wiring
- Blown fuse or open circuit in heater power supply
- Damaged connector or corroded terminals
- Faulty PCM (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Failed emissions test
- Possible poor fuel economy
- Rough idle or hesitation (less common)
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P0064 and check freeze frame data.
Step 2: Visually inspect the O2 sensor connector and wiring for damage, corrosion, or shorts.
Step 3: Measure voltage at the heater circuit with key on, engine off; should be battery voltage (12V). If higher, suspect short to power.
Step 4: Test resistance of the heater element; typically 2-10 ohms. If open or shorted, replace sensor.
Step 5: Check fuses related to O2 sensor heater circuit; replace if blown.
4. 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 $50-$150 for a DIY sensor replacement; labor at a shop adds $50-$100.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.