O2 Sensor Heater Control Circuit Low (Bank 2 Sensor 3)
The P0063 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the heater control circuit for the oxygen sensor located after the catalytic converter on bank 2 (the side of the engine not containing cylinder #1). This sensor is responsible for monitoring catalyst efficiency. The heater circuit helps the sensor reach operating temperature quickly. A low voltage reading suggests a short to ground, open circuit, or a faulty sensor.
01. Most Common Causes
- Faulty oxygen sensor (Bank 2 Sensor 3)
- Open or shorted heater circuit wiring
- Blown fuse or relay for O2 sensor heater
- Corroded or damaged connector
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Increased emissions
- Possible poor fuel economy
- Failed emissions test
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 loose connections.
Step 3: Test the heater circuit resistance at the sensor connector (typically 2-10 ohms).
Step 4: Check for battery voltage and ground at the heater circuit with the key on.
Step 5: If voltage and ground are present but sensor resistance is out of spec, replace the sensor.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but it may cause increased emissions and reduced fuel economy. It's best to fix it soon to avoid failing an emissions test.
How much does it cost to fix?▼
Typically $150-$300 for parts and labor, depending on the vehicle and shop rates.