P0167
O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 3)
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P0167 means the PCM has detected a problem in the heater circuit for the third oxygen sensor on Bank 2. This sensor's built-in heater is designed to bring the sensing element up to its operating temperature of approximately 600°F within seconds of engine start. Without the heater, the sensor must wait for hot exhaust gases to gradually warm it up, which can take several minutes.
The practical impact of this code is mostly limited to the first few minutes after a cold start. During this warm-up period, the sensor cannot provide accurate readings, so the PCM cannot monitor the secondary catalytic converter. Once the engine and exhaust system reach normal operating temperature, the sensor will function normally even without the heater. This makes the code more problematic for vehicles used primarily for short trips.
The heater element is integrated into the O2 sensor assembly and cannot be serviced separately, so the standard fix is full sensor replacement. However, always check the heater circuit fuse first — it is a common and inexpensive cause. Also inspect the heater circuit wiring and ground connections, particularly at points where the harness passes near exhaust components that could cause heat damage.
Severity
Symptoms
- •Check Engine Light is on
- •Longer engine warm-up period
- •Slightly rough cold idle
- •Reduced fuel economy on short trips
- •Failed emissions test
- •No significant symptoms when engine is warm
Likely Causes
The internal heater element in the third oxygen sensor on Bank 2 has failed due to age, preventing the sensor from reaching operating temperature without relying on exhaust heat alone.
A broken, shorted, or corroded wire in the heater power or ground circuit is preventing current from reaching the heater element.
The fuse that powers the O2 sensor heater circuits has blown, cutting power to the heater element.
A corroded or loose ground connection for the sensor heater circuit is preventing adequate current flow through the heater element.
The PCM's internal transistor that controls the heater circuit for this sensor has failed.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Replace the Bank 2 Sensor 3 oxygen sensor
- Check and replace the O2 sensor heater fuse
- Repair heater circuit wiring and ground connections
- Clean or replace corroded connectors in the heater circuit