Check engine light on: Codes, Causes & Fixes
A steady check engine light means the engine computer has stored a fault that affects emissions or engine management. In most cases you can keep driving normally for now, but have the code read soon – many auto parts stores and any OBD-II scanner can do this. If the light came on right after refueling, check that the gas cap is tight; loose caps are a classic trigger for EVAP codes.
558Codes
2.7Average severity
12%High or critical
18%DIY-friendly
Severity distribution
Most viewed
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
All codes (331)
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
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
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
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
P2188
Powertrain
At idle, bank 1 gets extra fuel from somewhere the PCM doesn't control; above idle the mixture…
Moderate
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