OBD codes / P0167
P0167
ModerateO2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 3)
Fine to drive — the engine's fuel control does not depend on this far-downstream sensor, and a slow-warming monitor sensor is an emissions bookkeeping problem, not a mechanical one. Sort it out before your next OBD inspection, and start the diagnosis at the fuse box.
What this code means
Every modern oxygen sensor has a built-in electric heater that brings it up to operating temperature within a minute or two of a cold start, long before the exhaust alone could. P0167 means the heater circuit for the bank 2, sensor 3 position — the sensor after the second catalytic converter, fitted only on some vehicles — has failed its electrical checks: the computer sees too much current, too little, or none at all. The most common cause is the heater element inside the sensor burning out, which means replacing the sensor since the heater is not serviceable separately. A blown fuse, a failed heater relay or driver, and wiring faults round out the list. Until it is fixed, the sensor warms slowly or not at all, so this code frequently drags a no-activity code like P0166 along with it.
Symptoms you might notice
- Check-engine light, often soon after a cold start
- No drivability symptoms
- Catalyst or O2 monitors failing to complete
- Sometimes paired with P0166 (no activity from the same sensor)
What it costs to fix
Typical range: $80–$450 · about ~0.2–1.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| O2 sensor replacement (heater is built in) | $30–$200 | ~0.3–1 hrs |
| Fuse or relay | $5–$40 | ~0.2–0.5 hrs |
| Wiring repair (heater power or ground) | $5–$60 | ~0.5–1.5 hrs |
A fuse-first diagnosis costs minutes and can save a sensor purchase — heater circuits often share a fuse with other sensors, so multiple heater codes at once strongly suggest a fuse or relay rather than several sensors dying together.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0167 for my exact vehicle →
Frequently asked
Why do oxygen sensors need heaters at all?
They only produce accurate readings when very hot. Exhaust heat alone would take a long time to warm a sensor this far downstream — if it ever fully does. The built-in heater gets it working within a minute or two of start-up, so emissions monitoring begins almost immediately.
Can I replace just the heater in the sensor?
No — the heater element is sealed inside the sensor body, so a burned-out heater means a new sensor. The good news is that if the fault is instead a fuse, relay, or wire, the sensor itself is usually still fine and the fix is cheap.
I have heater codes for more than one sensor. What does that suggest?
A shared cause. Multiple heater circuits often run through one fuse or relay, and it is far more likely that a single fuse blew than that several sensors failed simultaneously. Check the fuse and relay before pricing sensors.
Will P0167 affect fuel economy or performance?
Not measurably. This sensor monitors the second catalytic converter rather than steering the fuel mixture. The practical costs are the lit check-engine light, an inspection fail in OBD-tested areas, and suspended monitoring of that converter.
Seeing P0167 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0167 for my vehicleRelated trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0167 from your phone — see our honest guide to the best OBD2 Bluetooth adapters.
Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.