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 P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0420 Powertrain The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly. Low P0430 Powertrain The bank 2 converter on a V6, V8 or split-exhaust engine isn't cleaning the exhaust well enough. Low P0101 Powertrain The MAF sensor's airflow reading doesn't match what the engine computer expects… Low

P0001 Powertrain The PCM can't drive the solenoid that meters fuel into the high-pressure pump. Often a no-start… High P0016 Powertrain The bank 1 intake cam and the crankshaft are out of step, most often from a stretched or jumped… High P0018 Powertrain The bank 2 intake cam is out of step with the crankshaft on a V or boxer engine; chain wear… High P0087 Powertrain Measured fuel pressure has dropped well below what the engine computer is asking for. High P0093 Powertrain Rail pressure is dropping faster than injection explains: fuel may be escaping. Stop and check… Critical P0200 Powertrain The ECU found a fault in the injector control circuits that it can't pin on one cylinder, often… High P0216 Powertrain The ECU can't control or confirm injection timing, usually on a diesel with an electronic… High P0217 Powertrain The engine overheated. Stop driving: continuing can warp the head, blow the head gasket… Critical P0218 Powertrain The transmission fluid got hotter than the computer allows, from heavy load, low fluid… High P0231 Powertrain Voltage on the wire feeding the fuel pump is too low while the pump is supposed to be running. High P0234 Powertrain Boost rose above the safe limit the engine computer allows, so it may cut power to protect… High P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0320 Powertrain The computer lost the engine speed (rpm) signal. The engine can stall suddenly or refuse… High P0335 Powertrain The engine computer lost the crankshaft position signal. Expect stalling or a crank-no-start. High P0337 Powertrain The crank sensor signal line is stuck near 0 volts, usually a wire shorted to ground. Often… High P0338 Powertrain The crank signal line sits at 5 or 12 volts and stops switching: open ground, open wire… High P0339 Powertrain The crank signal drops out for moments at a time. Classic sign: stalls when hot, restarts once… High P0521 Powertrain The oil pressure reading doesn't fit engine speed and temperature – a drifting sensor or truly… High P0524 Powertrain Measured oil pressure fell below the safe minimum. Stop the engine now and check the oil before… Critical P0641 Powertrain The PCM's shared 5-volt supply 'A' is missing or out of range – often one shorted sensor… High P0642 Powertrain The PCM's 5-volt supply 'A' is being pulled below spec, usually by a short to ground in one… High P0685 Powertrain The engine computer can't switch its own main power relay – open coil, blown fuse or broken… High P06DD Powertrain The ECM commanded an oil pressure change and the measured pressure didn't respond – check… High P0730 Powertrain The transmission computer sees input and output shaft speeds that don't fit the gear it… High P0742 Powertrain The converter lockup clutch stays applied when it should be released, which can stall… High P0751 Powertrain Solenoid A is wired fine but its valve isn't doing its job, so gears are missing – often stuck… High P0756 Powertrain Solenoid B isn't moving fluid the way the TCM expects – the car may pull away in 3rd or 4th. High P0868 Powertrain Measured transmission line pressure is below what the TCM commanded – clutches can slip… High P0894 Powertrain The transmission computer measured slip inside the gearbox that shouldn't be there. Clutches… High P0A0F Powertrain The hybrid system spun the gas engine with its motor-generator to start it, but the engine… High