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

P0342 Powertrain The bank 1 cam sensor signal stays near 0 volts. Often a weak battery, a pinched wire… Moderate P0343 Powertrain The bank 1 cam signal is stuck high: an unlatched connector, broken ground or open wire after… Moderate P0344 Powertrain The bank 1 cam sensor signal keeps dropping out for short moments, which can cause random… Moderate P0345 Powertrain The cam sensor on bank 2, the side without cylinder 1, has a missing or faulty signal on a V6… Moderate P0346 Powertrain Bank 2's cam signal arrives out of position. On V6/V8s that often means a bank 2 chain, guide… Moderate P0350 Powertrain The shared coil feed, ignition module or coil wiring is faulty. Often set with several… Moderate P0351 Powertrain The engine computer found an electrical fault in coil A, the coil that fires cylinder 1 on most… Moderate P0352 Powertrain Coil B, normally on cylinder 2, has a circuit fault. Where cylinder 2 sits depends… Moderate P0353 Powertrain The circuit for coil C, which fires cylinder 3, failed its electrical check. Wiring is a big… Moderate P0354 Powertrain Coil D, normally the one on cylinder 4, failed its circuit check. It often shows up right after… Moderate P0355 Powertrain Coil E, the coil for cylinder 5, has an electrical fault. Only engines with five or more… Moderate P0356 Powertrain The coil F circuit for cylinder 6 failed its check. On inline sixes it's the coil… Moderate P0357 Powertrain Coil G, which fires cylinder 7 on V8s, has an electrical fault. On GM trucks it sits by… Moderate P0358 Powertrain Coil H, for cylinder 8, has an electrical fault. On nearly every V8 it's the hardest coil… Moderate P0366 Powertrain Bank 1 exhaust cam signal is out of position: chain stretch, a sticky exhaust phaser… Moderate P0402 Powertrain More exhaust is being recirculated than the ECU asked for, usually because the EGR valve won't… Moderate P0471 Powertrain The exhaust backpressure reading doesn't match what the computer expects; the sensor tube… Moderate P0472 Powertrain Exhaust backpressure sensor signal near zero volts: dead sensor, grounded wire or lost 5 V… Moderate P0480 Powertrain Fault in the circuit that switches the main radiator fan – the engine can overheat in traffic. Moderate P0500 Powertrain The engine computer lost its vehicle speed signal – speedometer, shifting and cruise control… Moderate P0504 Powertrain The two contacts in the brake pedal switch disagree on whether you're braking; check the pedal… Moderate P0520 Powertrain The engine computer gets a signal from the oil pressure sensor or switch that makes no… Moderate P0521 Powertrain The oil pressure reading doesn't fit engine speed and temperature – a drifting sensor or truly… High P0522 Powertrain The oil pressure signal is below what a working sensor can produce – usually wiring… Moderate P0524 Powertrain Measured oil pressure fell below the safe minimum. Stop the engine now and check the oil before… Critical P052E Powertrain The crankcase ventilation regulator isn't controlling crankcase pressure properly – often… Moderate P0560 Powertrain The engine computer saw its supply voltage missing or out of range – check fuses and feeds… Moderate P0562 Powertrain The engine computer sees too little supply voltage – usually a charging, battery or ground… Moderate P0563 Powertrain The engine computer sees too much supply voltage – usually an overcharging alternator cooking… Moderate P0572 Powertrain The PCM never sees the brake pedal pressed – brake lights may be out and the car may not shift… Moderate