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

C0020 Chassis The ABS module saw a fault in the electric pump motor that builds brake pressure during ABS… Moderate C0021 Chassis The brake module thinks the power brake booster isn't giving the assist it should. Check pedal… High C0035 Chassis The ABS module lost a valid signal from the driver-side front wheel speed sensor. Moderate C0040 Chassis The ABS module isn't getting a usable signal from the passenger-side front wheel speed sensor. Moderate C0045 Chassis The ABS module lost a valid signal from the driver-side rear wheel speed sensor. Moderate C0050 Chassis The ABS module can't trust the passenger-side rear wheel speed signal and has shut ABS off. Moderate C0055 Chassis The ABS module lost the combined rear-axle speed signal used on many GM trucks, vans and SUVs. Moderate C0110 Chassis The GM brake module (EBCM) found a fault in the ABS pump motor circuit and switched ABS off. Moderate C0121 Chassis The GM brake module can't confirm power to the ABS solenoid valves through its valve relay. Moderate C0131 Chassis The GM brake module sees an implausible or out-of-range signal from the brake pressure sensor. Moderate C0161 Chassis The GM brake module gets a brake-light switch signal that doesn't make sense. Check your brake… Moderate C0265 Chevrolet · Chassis The ABS module on many GM trucks found its built-in relay isn't delivering power, so ABS shuts… Moderate C0545 Chevrolet · Chassis The electric power steering module can't trust its torque sensor, so steering assist may cut… High C0550 Chassis A GM chassis module, most often the brake module (EBCM), failed its own internal self-check. Moderate C0561 Chassis GM's brake or chassis module switched off stability/traction control because of a fault… Low C1130 Nissan · Chassis The ABS/VDC unit isn't getting a valid engine signal from the ECM, so it switches stability… Moderate C1145 Ford · Chassis Ford's ABS module found an open or short in the right front (passenger-side) wheel speed sensor… Moderate C1155 Ford · Chassis Ford's ABS module saw the left front (driver-side) sensor circuit go open or shorted, often… Moderate C1165 Ford · Chassis Ford's ABS module detected an open or short in the right rear wheel speed sensor wiring… Moderate C1175 Ford · Chassis Electrical fault in the left rear sensor circuit, or in the single rear-axle sensor on some… Moderate C1185 Ford · Chassis The ABS module's internal power relay isn't delivering voltage to the valves and pump, so ABS… Moderate C1201 Toyota · Chassis The engine computer reported a fault, so the ABS/VSC unit switched stability and traction… Low C121C Jeep · Chassis The ESC module asked the engine to cut power and the PCM refused, so stability and traction… Low C1223 Toyota · Chassis The stability control side of the system has been told that ABS has a fault, so VSC and TRAC… Moderate C1233 Ford · Chassis The left front sensor wiring checks out, but no speed pulses reached the ABS module while… Moderate C1234 Ford · Chassis While driving, the right front speed signal dropped out or disagreed with the other wheels. Moderate C1241 Toyota · Chassis The ABS/stability control computer saw its supply voltage drop too low, so it shut the systems… Low C1252 Toyota · Chassis The brake pressure pump ran far longer than normal without reaching or holding its target… High C1253 Toyota · Chassis The brake ECU sees a pump motor relay or its monitor line not doing what it was told to do. Moderate C1256 Toyota · Chassis The brake system's high-pressure accumulator is below its minimum, so power brake assist can't… Critical