P0141
PowertrainO2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2)
The heater circuit on the bank 1 sensor 2 (rear) oxygen sensor has a fault, specifically a heater performance issue. The heater is what brings the sensor up to operating temperature within seconds of starting; without it, the sensor takes minutes to start working properly.
ⓘ Information only. This page provides general educational information about fault code P0141. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0141 mean?
P0141 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2).
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light, often within a minute of cold start
- • Slightly worse fuel economy on short trips
- • Sometimes a small emissions increase during the warm-up phase
- • Drivability typically unaffected
Possible causes
Causes commonly associated with P0141, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Sensor heater element failed open (most common, age-related)
- 2. Blown fuse for the oxygen sensor heater circuit (often shared with the front sensor)
- 3. Wiring damage along the loom, exhaust heat fatigues insulation over years
- 4. Connector corroded, the rear sensor's connector is closer to the road and gets more weather
- 5. Bad ground connection at the sensor
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Check the heater fuse first, free and quick
- 2. Resistance-test the heater across the sensor's heater pins; healthy is 5-15 ohms, an open circuit reads infinite
- 3. Verify 12V supply to the heater terminal with ignition on
- 4. Inspect the connector for water, corrosion, salt damage
- 5. Check ground continuity back to the ECU
Common questions about P0141
Why do oxygen sensor heaters fail so often? +
The heater element is a thin resistive wire that gets heated to red-hot temperatures within seconds of every cold start, then cycles through wide temperature swings every drive. Over thousands of heat cycles, the element fatigues and eventually breaks. UK rear oxygen sensors typically last 80,000-120,000 miles before the heater goes; some last longer, some shorter. After 80k they're considered consumable items.
Could this affect my MOT? +
Code itself doesn't directly fail MOT, but if the engine warning light is on at the time of test, that's an automatic fail under post-2018 rules. Fix the underlying fault, drive a few cycles for the light to clear, then book the test.
I have P0141 and P0420 together, related? +
Possibly. With a non-working rear sensor, the ECU can't accurately monitor cat efficiency, and may eventually flag P0420 as a result. Alternatively, both could be independent age-related faults. Fix the P0141 first, the rear sensor is much cheaper than the cat. If P0420 persists after the sensor replacement, then look at the cat itself.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →