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

P2123 Powertrain The main gas pedal sensor reads near its full 5-volt supply or higher, even with your foot off… Moderate P2125 Powertrain The PCM lost a valid signal from the second, cross-check sensor in the gas pedal. Moderate P2127 Powertrain The second gas pedal sensor dropped below its minimum voltage, so the PCM can't verify pedal… Moderate P2128 Powertrain The second gas pedal sensor reads above its allowed maximum, so the pedal position can't be… Moderate P2135 Powertrain The two position signals inside the throttle body disagree, so the PCM can no longer trust… Moderate P2138 Powertrain The two sensors in the gas pedal report different pedal positions, so the PCM limits throttle… Moderate P2146 Powertrain The shared power feed for one group of injectors is open, so every injector in that group has… High P2149 Powertrain The shared supply to the second injector group dropped out, often an intermittent wiring fault… High P2176 Powertrain The PCM hasn't stored where the closed throttle sits, usually after a battery disconnect… Low P2177 Powertrain Bank 1 goes lean once the engine is above idle, so the PCM keeps adding fuel at cruise… Moderate P2178 Powertrain Above idle, bank 1 carries more fuel than the PCM asked for, and pulling fuel out no longer… Moderate P2181 Powertrain The engine isn't warming up or holding temperature the way the computer's model says it should. Low P2187 Powertrain Bank 1 runs lean at idle but recovers once rpm rises, the classic fingerprint of unmetered air. Low P2188 Powertrain At idle, bank 1 gets extra fuel from somewhere the PCM doesn't control; above idle the mixture… Moderate P2195 Powertrain The front O2 or air-fuel sensor keeps reading lean while the rear sensor shows the engine isn't… Low P2196 Powertrain The front sensor on bank 1 keeps claiming rich, so the PCM strips out fuel the engine actually… Low P2197 Powertrain The upstream sensor on the bank without cylinder 1 reads lean while the other checks say that… Low P2198 Powertrain Bank 2's front sensor keeps claiming rich, so the PCM leans out that side of the engine more… Low P219A Powertrain One cylinder on bank 1 runs clearly richer or leaner than the others, even if the average looks… Moderate P219B Powertrain One cylinder on bank 2 runs off the mixture of the other cylinders on that side of the engine. 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 P2204 Powertrain The upstream NOx sensor signal keeps dropping out or jumping around for short moments. Low P2209 Powertrain The heater in the upstream NOx sensor can't reach or hold its working temperature properly. Low P2226 Powertrain The engine computer can't get a valid reading from its barometric (ambient air pressure) sensor. Low P2227 Powertrain The baro sensor's reading doesn't agree with the other pressure sensors or with what the engine… Low P2228 Powertrain The baro sensor signal is below its valid range, as if the car were far higher than any road… Moderate P2237 Powertrain The wire that carries the pump current of the upstream wideband (air-fuel) sensor is open. Low