Fuel & Air Metering Trouble Codes: List & Fixes

These codes (mostly P00xx–P02xx) cover how the engine computer measures incoming air and meters fuel: the mass airflow and manifold pressure sensors, oxygen sensors, fuel trim, fuel pressure and injectors. Lean codes such as P0171 and P0174 are very often caused by an unmetered air leak – a cracked intake hose or vacuum line – rather than a failed sensor. Check hoses and the air filter housing before buying parts.

193Codes

2.5Average severity

7%High or critical

26%DIY-friendly

Severity distribution

Most viewed

P0174 Powertrain The cylinder bank without cylinder 1 is running lean even with the maximum fuel correction… Moderate 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 P0172 Powertrain The engine computer is pulling as much fuel as it's allowed on bank 1 and the mixture is still… Moderate

All codes (193)

All Severity 3+ Severity 4+

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 P2646 Powertrain The engine asked VTEC to switch to the high-lift cam, but the oil pressure switch never saw… Low P2647 Powertrain The VTEC oil pressure switch reports the high-lift rockers engaged while the engine computer… Moderate

Subsystems

Emission Controls 97 Ignition & Misfire 66 Speed & Idle Control 57 Transmission 57 ECU & Outputs 54 Module Communication 43 Brakes, ABS & Chassis 36 Body Systems 31 Hybrid / EV 14