Check engine light on: Codes, Causes & 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 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

P2002 Powertrain The ECU thinks the diesel particulate filter isn't trapping soot properly — or it can't measure… Moderate P2004 Powertrain The intake runner or tumble flaps stay open when told to close, usually a vacuum or linkage… Low P2006 Powertrain The intake swirl or runner flaps stay shut when the ECU wants them open, choking airflow… Moderate P2009 Powertrain The runner or tumble flap solenoid circuit reads too low: a short to ground, an open coil… Low P200A Powertrain The ECU switched the intake runner flaps but the system didn't respond the way it should. Low P2015 Powertrain The sensor on the intake manifold flaps reports a position that doesn't match what the ECU… Low P204F Powertrain The DEF/SCR system isn't cutting NOx the way it should; ignored, it leads to a severe speed… Moderate P207F Powertrain The ECM thinks the DEF in the tank is too weak or contaminated, often right after a refill. Moderate P2096 Powertrain The sensor behind the catalytic converter keeps reporting lean, and the ECU has run out of room… Low P2097 Powertrain The sensor behind the converter keeps seeing rich exhaust, and the ECU can't lean the mixture… Low P20E8 Powertrain The DEF pump can't build or hold enough pressure; suspect a leak, frozen line, clogged filter… Moderate P20EE Powertrain The SCR catalyst isn't removing enough NOx; DEF quality, dosing, a NOx sensor or the catalyst… Moderate P2100 Powertrain The computer can't push current through the throttle motor – the circuit to the throttle body… High P2101 Powertrain The throttle plate isn't reaching the position the computer asks for, fast enough or accurately… Moderate P2102 Powertrain Too little current or voltage reaches the throttle motor – usually resistance in the feed, not… Moderate P2103 Powertrain The throttle motor circuit draws too much current – a short, a shorted motor or a plate that… Moderate P2104 Powertrain A fail-safe has locked the engine at idle and the gas pedal no longer works – another code… High P2105 Powertrain The engine computer shut the engine off on purpose because it could no longer control… Critical P2106 Powertrain Reduced-power limp mode: the PCM caught a throttle or pedal fault – look for the companion code. Moderate P2107 Powertrain The processor supervising the electronic throttle failed its self-check – a computer fault, not… High P2108 Powertrain The throttle control module isn't performing as expected – check its power, data link… Moderate P2109 Powertrain The closed-throttle reading no longer matches what the computer learned – usually carbon… Low P2110 Powertrain The PCM is capping engine speed with fuel cut-off because it can't fully trust or close… Moderate P2111 Powertrain The throttle plate stayed more open than commanded – a real safety concern until you know why. High P2112 Powertrain The PCM asked the throttle to open, but it stayed shut – the engine can't get air, so it bogs… High P2118 Powertrain The throttle motor is drawing more or less current than the PCM expects to hold the plate where… Moderate P2119 Powertrain The throttle plate isn't reaching the position the PCM commands, or won't spring back to its… Moderate P2120 Powertrain The PCM lost a usable signal from the main gas pedal sensor, often only for a moment. Moderate P2121 Powertrain The main gas pedal signal stays within normal voltage but moves in a way a real pedal can't. Moderate P2122 Powertrain The main gas pedal sensor reads close to 0 volts, below anything a working pedal produces… Moderate