OBD-II Trouble Codes: Meaning & Fixes

C0035 Chassis The ABS module lost a valid signal from the driver-side front wheel speed sensor. Moderate 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 B0001 Body The airbag module found a fault in the firing circuit for the driver's front airbag (stage 1). High 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

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 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 P2228 Powertrain The baro sensor signal is below its valid range, as if the car were far higher than any road… Moderate P2262 Powertrain The engine computer commanded boost but saw almost none, pointing to a mechanical turbo… Moderate P2263 Powertrain Boost isn't tracking its target closely enough: too low, too high or too slow to respond. Moderate P2293 Powertrain The second fuel pressure control stage can't hold its target; on VW/Audi 2.0T often… Moderate P229F Powertrain The NOx sensor after the SCR catalyst is sending believable-looking but wrong or sluggish… Moderate P242F Powertrain The DPF is filling up with ash that regeneration can't burn off; it needs cleaning… Moderate P2440 Powertrain The valve that should seal the air pump off from the bank 1 exhaust stays open, letting hot… Moderate P2442 Powertrain The bank 2 secondary air valve on a V engine doesn't seal, so exhaust pulses reach the air pump… Moderate P244A Powertrain The pressure drop across the DPF is lower than physically expected: a hose is off… Moderate P244B Powertrain The DPF is resisting exhaust flow far more than it should – usually a filter packed with soot… Moderate P2452 Powertrain The ECU has lost a usable signal from the DPF pressure sensor – usually a wiring, connector… Moderate P2453 Powertrain The DPF pressure reading doesn't make sense for the exhaust flow – most often a hose or tube… Moderate P2454 Powertrain The DPF pressure sensor's signal voltage has dropped below the lowest value a working sensor… Moderate P2455 Powertrain The DPF pressure signal is stuck above its valid range – a wiring fault, or a filter that's… Moderate P2457 Powertrain The EGR cooler isn't cooling the recirculated exhaust enough – it's clogged, bypassed or low… Moderate