Check engine light on: Codes, Causes & Fixes

P0135 Powertrain The heater inside the upstream oxygen sensor on bank 1 isn't working or its circuit is faulty. Low P0174 Powertrain The cylinder bank without cylinder 1 is running lean even with the maximum fuel correction… Moderate P0113 Powertrain The intake air temperature signal is stuck at maximum voltage, which usually means an open… 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 P0299 Powertrain The turbo or supercharger isn't building the boost pressure the engine computer is asking for. Moderate

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 P2228 Powertrain The baro sensor signal is below its valid range, as if the car were far higher than any road… Moderate 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 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 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 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 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