P0161: Oxygen sensor heater (bank 2, sensor 2): circuit fault
The heater in the bank 2 oxygen sensor after the catalytic converter has a fault. Usually a blown fuse, the connector or the sensor itself.
| Code | P0161 |
|---|---|
| System | Engine and transmission |
| Group | P01xx, Air and fuel metering |
| Type | Generic: it means the same on every make |
| Can you keep driving? | Yes, no rush |
What P0161 means
The oxygen sensor after the catalytic converter is mainly there to check that the converter is cleaning the exhaust properly; it has little effect on how the engine runs. The sensor only works when it is very hot, so it has a small built-in heater that warms it up after a cold start. This code means the heater circuit has a fault. Bank 2 is the side of the engine opposite cylinder 1, and it only exists on V-shaped or boxer engines.
Most common causes
- Blown fuse for the oxygen sensor heaters
- Sensor connector loose or corroded
- Broken supply or earth wire to the heater
- Burnt-out heater element inside the sensor (the most common cause; the sensor has to be replaced)
- Faulty relay or ECU supply to the heater
Symptoms
- Engine warning light on
- The car drives normally
- Some of the ECU’s emissions self-tests never complete
Can you drive with P0161?
Yes, no rush You can keep using the car normally. Fix it when convenient, but before the next inspection, as a lit warning light means a fail.
Open the bonnetthe in-depth explanation
How to check it
Look in the handbook for the fuse that feeds the oxygen sensor heaters and check it. If it is fine, a garage can measure the heater resistance at the sensor connector: with no continuity, the sensor needs replacing.
How to read and clear P0161 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0161 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P015B Heated lambda sensor 1 on bank 1 is late switching from lean to rich
- P015C Heated lambda sensor 1 on bank 2 is late switching from rich to lean
- P015D Heated lambda sensor 1 on bank 2 is late switching from lean to rich
- P0160 Oxygen sensor (bank 2, sensor 2): no activity
- P0162 The lambda sensor (bank 2, sensor 3) has an electrical fault
- P0163 The lambda sensor (bank 2, sensor 3) gives a lower signal than normal
- P0164 The lambda sensor (bank 2, sensor 3) gives a higher signal than normal
- P0165 The lambda sensor circuit (bank 2, sensor 3) responds slowly
- P0100 Mass or volume air flow sensor circuit fault
- P0101 Air flow sensor range or performance problem
- P0102 Air flow sensor circuit low input
- P0103 Air flow sensor circuit high input
What does code P0161 mean?
The oxygen sensor after the catalytic converter is mainly there to check that the converter is cleaning the exhaust properly; it has little effect on how the engine runs. The sensor only works when it is very hot, so it has a small built-in heater that warms it up after a cold start. This code means the heater circuit has a fault. Bank 2 is the side of the engine opposite cylinder 1, and it only exists on V-shaped or boxer engines.
Can you drive with P0161?
You can keep using the car normally. Fix it when convenient, but before the next inspection, as a lit warning light means a fail.
How do you clear P0161?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0161 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
