O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 3)
The P0167 code indicates a malfunction in the heater circuit of the oxygen sensor located after the catalytic converter on Bank 2 (the side of the engine not containing cylinder #1). The heater element is essential for the sensor to reach operating temperature quickly, especially during cold starts. When the powertrain control module (PCM) detects an abnormal current draw or resistance in the heater circuit, it sets this code. This can lead to inaccurate air-fuel ratio readings, increased emissions, and potential catalytic converter damage if left unresolved.
1. Most Common Causes
- O2 sensor (Bank 2 Sensor 3) with internal heater element failure
- Open or short circuit in the heater circuit wiring
- Short to ground or battery voltage (B+) in the heater circuit
- Corroded, disconnected, or bent/pitted pins in the sensor connector
- Blown or defective fuse or relay in the O2 sensor heater power supply circuit (if applicable)
- Excessive electrical resistance due to deteriorated splices or connection points in the harness
- Internal failure of the Powertrain Control Module (PCM)
2. Symptoms You Will Notice
- Illuminated Check Engine Light
- Failed emissions test
- Poor fuel economy
- Rough idle or hesitation
- Possible sulfur smell from exhaust
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for additional 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 using a multimeter (typically 2-10 ohms).
Step 4: Check the heater circuit fuse and relay for continuity.
Step 5: If all else is fine, replace the oxygen sensor.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances, but it may cause poor fuel economy and increased emissions. Prolonged driving can damage the catalytic converter, so it's best to address it promptly.
How much does it cost to fix?▼
The cost typically ranges from $150 to $300, including parts and labor. The sensor itself costs $50-$150, and labor adds $50-$150 depending on accessibility.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.