P2195: O2 sensor signal stuck lean (bank 1 sensor 1)
The oxygen sensor in front of the catalytic converter keeps reading lean, even when the engine computer adds fuel to correct it. Either the mixture really is lean, or the sensor’s reading is wrong.
Updated
What P2195 means
On most petrol engines the engine computer keeps nudging the mixture slightly richer and leaner, and the oxygen sensor in front of the catalytic converter (sensor 1) should follow. P2195 means that sensor’s signal stays lean on bank 1: even when the engine computer adds fuel, the reading doesn’t move.
That can mean two things: the mixture really is lean, for example from an air leak, or the sensor or its wiring gives a wrong reading. Other codes stored at the same time often show which.
Read My Car shows short and long term fuel trim under Live data, if your car reports them.
P2196 to P2198, and the rear sensors (P2270 to P2273)
P2196 is the opposite: the sensor stays rich. P2197 and P2198 are the same two faults on bank 2 of a V or flat engine, the side without cylinder 1.
P2270 to P2273 are the same checks on sensor 2, behind the catalytic converter. That sensor mainly checks the converter, so these codes rarely change how the car drives; the sensor itself, its wiring or an exhaust leak near it are the usual causes.
P2196: O2 Sensor Signal Stuck Rich (Bank 1, Sensor 1)
The oxygen sensor in front of the catalytic converter keeps reading rich, even when the engine computer takes fuel away to correct it. Either the mixture really is rich, or the sensor’s reading is wrong.
Common causes: leaking injector, fuel pressure too high, faulty oxygen sensor or its wiring, dirty or faulty air flow (maf) sensor.
P2197: O2 Sensor Signal Stuck Lean (Bank 2, Sensor 1)
P2198: O2 Sensor Signal Stuck Rich (Bank 2, Sensor 1)
The oxygen sensor in front of the catalytic converter keeps reading rich, even when the engine computer takes fuel away to correct it. Either the mixture really is rich, or the sensor’s reading is wrong.
Common causes: leaking injector, fuel pressure too high, faulty oxygen sensor or its wiring, dirty or faulty air flow (maf) sensor.
P2270: O2 Sensor Signal Stuck Lean (Bank 1, Sensor 2)
The oxygen sensor behind the catalytic converter keeps reading lean when the engine computer expects its reading to change. This sensor mainly checks the converter, so the engine usually runs normally.
Common causes: faulty oxygen sensor, exhaust leak near the sensor, wiring or connector fault.
P2271: O2 Sensor Signal Stuck Rich (Bank 1, Sensor 2)
The oxygen sensor behind the catalytic converter keeps reading rich when the engine computer expects its reading to change. This sensor mainly checks the converter, so the engine usually runs normally.
Common causes: faulty or contaminated oxygen sensor, wiring or connector fault, a rich mixture, for example from a leaking injector.
P2272: O2 Sensor Signal Stuck Lean (Bank 2, Sensor 2)
The oxygen sensor behind the catalytic converter keeps reading lean when the engine computer expects its reading to change. This sensor mainly checks the converter, so the engine usually runs normally.
Common causes: faulty oxygen sensor, exhaust leak near the sensor, wiring or connector fault.
P2273: O2 Sensor Signal Stuck Rich (Bank 2, Sensor 2)
The oxygen sensor behind the catalytic converter keeps reading rich when the engine computer expects its reading to change. This sensor mainly checks the converter, so the engine usually runs normally.
Common causes: faulty or contaminated oxygen sensor, wiring or connector fault, a rich mixture, for example from a leaking injector.
Can I keep driving?
Check soon
Probably OK to drive short-term, but have it checked soon. Fuel use or emissions may be worse.
General guidance based on the code alone, not on the car’s actual condition. If in doubt, stop and ask a mechanic.
The engine usually keeps running, but a mixture that really is lean or rich can make it misfire and, over time, damage the catalytic converter. If misfire codes appear too, avoid hard driving. If the check engine light flashes, stop when it’s safe to do so.
Symptoms
- Often just the check engine light.
- Higher fuel use, or a rough idle or hesitation on some cars.
- Lean or rich codes, such as P0171 or P0172, stored at the same time.
Common causes
- Vacuum or intake air leak. Unmeasured air makes the mixture really lean. A lean code (P0171) stored at the same time points this way.
- Exhaust leak in front of the sensor. Outside air drawn in through the leak makes the sensor read lean when the mixture isn’t.
- Faulty oxygen sensor or its wiring. An aged or contaminated sensor, or a wiring fault, can hold the reading at lean.
- Low fuel pressure or a clogged injector. Too little fuel reaches the cylinders.
Typical fixes
- Read all fault codes, and fix lean, misfire and air flow sensor faults first.
- Look and listen for vacuum and intake leaks, and check the exhaust in front of the sensor for leaks.
- Check the sensor’s wiring and connector.
- Have the sensor’s signal checked in live data, and the fuel pressure tested if the sensor and the leak checks find nothing.
- Replace the sensor with the type specified for your car if it’s faulty, then clear the codes.
Questions
Can I drive with P2195?
Probably for a short time, but have it checked soon: fuel use or emissions may be worse. If the engine misfires or runs rough, avoid hard driving, and if the check engine light flashes, stop when it’s safe to do so.
Is P2195 the oxygen sensor or a vacuum leak?
It can be either. The code only says the sensor keeps reading lean. Rule out air and exhaust leaks, and check the wiring, before replacing the sensor.