P0160
PowertrainO2 Sensor Circuit No Activity Detected (Bank 2 Sensor 2)
This is usually a small job, often just a sensor swap, so don't let it worry you. The rear oxygen sensor on bank 2 (the side of the engine that doesn't have cylinder 1) has gone quiet. The ECU expects this sensor to switch and report back as the exhaust gas changes, and when it gets a flat line with no activity at all, it flags P0160. Most of the time it's a dead sensor or a broken bit of wiring back to it, not an engine problem.
ⓘ Information only. This page provides general educational information about fault code P0160. 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 P0160 mean?
P0160 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: O2 Sensor Circuit No Activity Detected (Bank 2 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 management light on, and frequently that's the only thing you'll notice
- • Fuel economy down a touch on some cars, though plenty of owners spot no difference at all
- • The odd rough idle or slight hesitation, but this is uncommon with a rear sensor fault
- • An emissions test that fails because the ECU can't complete its oxygen sensor readiness monitor
- • No drop in power or drivability in a lot of cases, the car drives exactly as it did before
Possible causes
Causes commonly associated with P0160, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. The bank 2 downstream sensor itself has failed, by far the most likely cause. The heater element or sensing element packs in and the signal goes flat
- 2. Wiring damage between the sensor and the loom. These run under the car near the exhaust and the heat eventually cooks the insulation
- 3. A dirty or corroded connector at the sensor plug, very common on cars that see a lot of winter salt
- 4. An exhaust leak near the sensor letting fresh air in and skewing what the sensor sees
- 5. A blown fuse or open in the sensor's power feed, which kills the heater so the sensor never reaches working temperature
- 6. ECM fault, rare, and only worth looking at once everything upstream has been ruled out
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. Get the connector unplugged and have a proper look at the pins and the wiring back along the loom. Burnt insulation, green corrosion or a chafed wire against the heat shield is what kills these, and it costs nothing to check
- 2. Back-probe the sensor with a multimeter and watch live data on a scanner at the same time. A working sensor will show some switching activity once warm. A dead flat line confirms no signal
- 3. Check the heater circuit has power and a good ground with the ignition on. If the heater fuse is gone the sensor will read as inactive even though it's fine
- 4. Look and listen for an exhaust leak ahead of the sensor, anything letting air in upstream will mess with the reading
- 5. If the wiring, power and ground all check out and the sensor still won't switch, fit a new sensor. Confirm related codes have cleared afterwards
Common questions about P0160
How long should this take to sort out? +
If it's a clean sensor swap you're looking at well under an hour at a garage, sometimes thirty to forty minutes once the car's up on the ramp. The thing that blows the time out is a seized sensor that won't budge. A baked-on sensor can chew up another half hour with heat and penetrating fluid, and if the thread strips you're then into a repair, so a garage will sometimes quote a bit of slack for that.
Can I fit a cheap aftermarket sensor or should I pay for the genuine one? +
A decent branded aftermarket sensor from the likes of Bosch, NGK or Denso is perfectly fine for a rear sensor and a fraction of dealer money. These are the same firms that make the original parts for most car makers anyway. What I'd steer you away from is the no-name £15 universal sensors you splice in yourself, they often play up and you end up doing the job twice. Buy the right plug-and-play part for your car and you'll be fine.
Is it alright to keep driving like this for a bit? +
For a rear sensor on bank 2, yes, you can drive on it short term without doing the engine any harm, since this one monitors the cat rather than controlling the fuel mixture. Your fuel economy might dip slightly and the light stays on, which means you won't pass an MOT while that lamp is lit. Get it booked in before your test is due rather than leaving it indefinitely.
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 →