Oxygen sensors
Oxygen sensors before and after the catalyst, their heaters and a stuck signal. They tell the unit what came out of the mixture — and the verdict on catalyst efficiency depends on them too.
19 codes in this section, 19 with a guide
What it usually turns out to be
- A slow sensor response is wear, not an open circuit: the code appears long before the car starts driving worse.
- Heater codes are often a fuse or a connector rather than the sensor itself.
- P0420 turns out to be the rear sensor more often than a dead catalyst.
P0130Upstream O2 sensor circuit malfunction (bank 1)guideP0131Upstream O2 sensor circuit low voltage (bank 1)guideP0132Upstream O2 sensor circuit high voltage (bank 1)guideP0133Upstream O2 sensor slow response (bank 1) — usually a worn sensorguideP0134Upstream O2 sensor no activity (bank 1) — open circuit or burnt sensorguideP0135O2 sensor heater circuit malfunction (bank 1, upstream)guideP0136Downstream O2 sensor circuit malfunction (bank 1)guideP0137Downstream O2 sensor circuit low voltage (bank 1)guideP0138Downstream O2 sensor circuit high voltage (bank 1)guideP0139Downstream O2 sensor slow response (bank 1)guideP0140Downstream O2 sensor no activity detected (bank 1)guideP0141O2 sensor heater circuit malfunction (bank 1, downstream)guideP0143O2 sensor circuit low voltage (bank 1, sensor 3)guideP0150Upstream O2 sensor circuit malfunction (bank 2)guideP0155O2 sensor heater circuit malfunction (bank 2, upstream)guideP0161O2 sensor heater circuit malfunction (bank 2, downstream)guideP2195Oxygen sensor (bank 1, upstream) — signal stuck leanguideP2196Oxygen sensor (bank 1, upstream) — signal stuck richguideP2197Oxygen sensor (bank 2, upstream) — signal stuck leanguide
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Other sections
Fuel and air metering, general 33Intake measuring sensors 17Throttle and accelerator pedal 15Mixture: lean and rich 11Fuel and air metering: injectors 25Ignition system and misfires 29Exhaust gas recirculation (EGR) 7Secondary air injection 3Catalytic converter 4Canister and purge valves 9Fuel vapour leaks 7Fuel level in the tank 4Diesel particulate filter 6Idle and auxiliary systems 22Control module and its circuits 21Transmission 17Communication between modules 20Brakes, ABS and stability control 17Body, airbags and lighting 12