OBD-II Trouble Codes: Meaning & Fixes

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 B0001 Body The airbag module found a fault in the firing circuit for the driver's front airbag (stage 1). High C0035 Chassis The ABS module lost a valid signal from the driver-side front wheel speed sensor. 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

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 P2442 Powertrain The bank 2 secondary air valve on a V engine doesn't seal, so exhaust pulses reach the air pump… Moderate P244A Powertrain The pressure drop across the DPF is lower than physically expected: a hose is off… Moderate P244B Powertrain The DPF is resisting exhaust flow far more than it should – usually a filter packed with soot… Moderate P2452 Powertrain The ECU has lost a usable signal from the DPF pressure sensor – usually a wiring, connector… Moderate P2453 Powertrain The DPF pressure reading doesn't make sense for the exhaust flow – most often a hose or tube… Moderate P2454 Powertrain The DPF pressure sensor's signal voltage has dropped below the lowest value a working sensor… Moderate P2455 Powertrain The DPF pressure signal is stuck above its valid range – a wiring fault, or a filter that's… Moderate P2457 Powertrain The EGR cooler isn't cooling the recirculated exhaust enough – it's clogged, bypassed or low… Moderate P2458 Powertrain A DPF regen took too long or never finished, usually from short trips or exhaust that won't get… Moderate P2459 Powertrain The DPF is regenerating far more often than it should for the miles driven. Moderate P2463 Powertrain The DPF is loaded with more soot than the ECU allows; it needs a regen or cleaning before it… High P246C Powertrain The DPF is so restricted that the ECM has cut engine power to protect the turbo, EGR system… High P2502 Powertrain The ECM distrusts the charging system – no output, wrong voltage or an implausible alternator… Moderate P2503 Powertrain The alternator can't reach the voltage the ECM asks for – usually a worn alternator or slipping… Moderate P2504 Powertrain The charging system is overcharging – too much voltage can boil the battery and damage… High P25A2 Chevrolet · Powertrain The brake module stored a fault and asked the engine computer to turn on the check engine light. 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 P26B7 Ford · Powertrain The PCM sees an open circuit to the electric coolant bypass valve on Ford's 1.6L EcoBoost… Moderate P2714 Powertrain Transmission pressure solenoid D isn't regulating pressure as commanded – a classic source… Moderate P2716 Powertrain The transmission computer sees an open or short in the circuit of pressure control solenoid D. Moderate P2BAC Powertrain EGR has been shut off because of a fault, so NOx is above the limit; fix the EGR code stored… Moderate P3000 Toyota · Powertrain Toyota's hybrid computer flags a fault in the high-voltage battery system and limits hybrid… High