Powertrain Codes (P-Codes): Full List
Powertrain codes start with P and cover the engine, fuel and ignition systems, emission controls and the transmission. They are the codes that most often turn on the check engine light and the ones most relevant to a smog check or emissions test. The third character narrows it down: 1–2 fuel and air metering, 3 ignition and misfire, 4 emission controls, 5 speed and idle, 6 computer and outputs, 7–9 transmission, A hybrid.
539Codes
2.7Average severity
12%High or critical
20%DIY-friendly
Severity distribution
Most viewed
P0174
Powertrain
The cylinder bank without cylinder 1 is running lean even with the maximum fuel correction…
Moderate
P0420
Powertrain
The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly.
Low
P0101
Powertrain
The MAF sensor's airflow reading doesn't match what the engine computer expects…
Low
P0113
Powertrain
The intake air temperature signal is stuck at maximum voltage, which usually means an open…
Low
P0135
Powertrain
The heater inside the upstream oxygen sensor on bank 1 isn't working or its circuit is faulty.
Low
P0171
Powertrain
The engine computer is adding the maximum extra fuel it's allowed on bank 1 and still sees…
Moderate
All codes (539)
P2200
Powertrain
The engine computer lost a usable signal from the NOx sensor ahead of the SCR catalyst on bank…
Moderate
P2201
Powertrain
The upstream NOx sensor still communicates, but its readings don't match what the ECM expects.
Moderate
P2202
Powertrain
The upstream NOx sensor reports a signal or internal circuit below its lower limit.
Moderate
P2203
Powertrain
The upstream NOx sensor reports a value or circuit stuck above its upper limit.
Moderate
P2204
Powertrain
The upstream NOx sensor signal keeps dropping out or jumping around for short moments.
Low
P2209
Powertrain
The heater in the upstream NOx sensor can't reach or hold its working temperature properly.
Low
P2226
Powertrain
The engine computer can't get a valid reading from its barometric (ambient air pressure) sensor.
Low
P2227
Powertrain
The baro sensor's reading doesn't agree with the other pressure sensors or with what the engine…
Low
P2228
Powertrain
The baro sensor signal is below its valid range, as if the car were far higher than any road…
Moderate
P2237
Powertrain
The wire that carries the pump current of the upstream wideband (air-fuel) sensor is open.
Low
P2238
Powertrain
The pump-current wire of the upstream air-fuel sensor is being pulled low, usually by a short…
Low
P2243
Powertrain
The ECM lost the reference-cell signal of the upstream wideband sensor, as if the wire were…
Low
P2262
Powertrain
The engine computer commanded boost but saw almost none, pointing to a mechanical turbo…
Moderate
P2263
Powertrain
Boost isn't tracking its target closely enough: too low, too high or too slow to respond.
Moderate
P2270
Powertrain
The oxygen sensor after the catalytic converter won't show rich, even when the PCM deliberately…
Low
P2271
Powertrain
The sensor after the converter stays rich even while coasting with the fuel cut off, when it…
Low
P2279
Powertrain
Air is getting into the engine after the mass airflow sensor, so the computer isn't measuring…
Low
P2293
Powertrain
The second fuel pressure control stage can't hold its target; on VW/Audi 2.0T often…
Moderate
P229F
Powertrain
The NOx sensor after the SCR catalyst is sending believable-looking but wrong or sluggish…
Moderate
P2400
Powertrain
The engine computer can't drive the EVAP leak detection pump – usually a broken wire, bad plug…
Low
P2401
Powertrain
The leak detection pump's control wire reads too low – most often a wire rubbing through…
Low
P2401
Toyota · Powertrain
In Toyota's key-off EVAP test, the canister module's leak detection pump didn't pull…
Low
P2402
Powertrain
The leak pump's control line reads too high – usually a short to a 12-volt wire…
Low
P2404
Powertrain
The switch that reports the leak pump's position isn't changing state the way it should during…
Low
P2419
Powertrain
Too little voltage on the EVAP switching (vent) valve control wire – wiring or canister pump…
Low
P2420
Powertrain
The switching valve in the EVAP canister pump module can't be switched – its control line stays…
Low
P2422
Powertrain
The EVAP vent path is blocked, so the tank can't breathe – slow refueling and a whoosh when…
Low
P242F
Powertrain
The DPF is filling up with ash that regeneration can't burn off; it needs cleaning…
Moderate
P2440
Powertrain
The valve that should seal the air pump off from the bank 1 exhaust stays open, letting hot…
Moderate
P2441
Powertrain
The air pump runs after a cold start, but the bank 1 valve won't open – no fresh air reaches…
Low