Chevrolet OBD Codes: Meaning & Fixes

P0420 Powertrain The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly. Low C0035 Chassis The ABS module lost a valid signal from the driver-side front wheel speed sensor. Moderate P0171 Powertrain The engine computer is adding the maximum extra fuel it's allowed on bank 1 and still sees… Moderate P0299 Powertrain The turbo or supercharger isn't building the boost pressure the engine computer is asking for. Moderate P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0304 Powertrain Cylinder 4 is misfiring. Its end or rear position makes water, oil and intake leaks common… Moderate

P0496 Powertrain Vapor is being drawn into the engine while purge is commanded off: almost always a purge valve… Low P0522 Powertrain The oil pressure signal is below what a working sensor can produce – usually wiring… Moderate P0597 Powertrain The electrically heated thermostat's heater circuit is open, so the ECU can't open it early… Low P0602 Powertrain The engine computer has no valid or complete software – typical after a module swap or a failed… Moderate P0621 Powertrain A fault in the alternator's 'L' circuit – the line behind the charge light or the ECM's turn-on… Moderate P0625 Powertrain The PCM sees the alternator's field-monitor signal stuck low – usually the regulator, its plug… Moderate P0642 Powertrain The PCM's 5-volt supply 'A' is being pulled below spec, usually by a short to ground in one… High P069E Chevrolet · Powertrain The fuel pump control module stored its own fault and asked the engine computer for the check… Moderate P06DD Powertrain The ECM commanded an oil pressure change and the measured pressure didn't respond – check… High P0700 Powertrain The transmission computer found a fault and asked for the check engine light – read the TCM… Moderate P0705 Powertrain The computer can't make sense of the gear selector position signal – P, R, N, D may be misread. Moderate P0731 Powertrain While in first gear, the transmission's input and output speeds don't match the first-gear… Moderate P0733 Powertrain Third gear slips: input shaft speed doesn't match output speed times the 3rd-gear ratio. Moderate P0735 Powertrain Fifth gear slips or isn't fully applied; the TCM measures a ratio that doesn't fit 5th. Moderate P0740 Powertrain The computer found an open or faulty circuit to the torque converter clutch solenoid, so lockup… Low P0741 Powertrain The torque converter lockup clutch slips or won't engage when the computer commands it. Moderate P0748 Powertrain The TCM detected an electrical fault (open, short or wrong current) in pressure control… Moderate P0750 Powertrain The transmission computer sees a fault in shift solenoid A or its circuit and can't use it… Moderate P0751 Powertrain Solenoid A is wired fine but its valve isn't doing its job, so gears are missing – often stuck… High P0753 Powertrain The control circuit for shift solenoid A reads open, shorted or out of range – an electrical… Moderate P0756 Powertrain Solenoid B isn't moving fluid the way the TCM expects – the car may pull away in 3rd or 4th. High P0894 Powertrain The transmission computer measured slip inside the gearbox that shouldn't be there. Clutches… High P1101 Chevrolet · Powertrain GM's engine computer found that measured airflow doesn't agree with what it expects. Low P1133 Chevrolet · Powertrain The front oxygen sensor on bank 1 isn't flipping between rich and lean often enough during GM's… Low P1134 Chevrolet · Powertrain Bank 1's front O2 sensor reacts much faster in one direction (rich or lean) than the other. Low P1153 Chevrolet · Powertrain The front O2 sensor on the passenger-side bank of a Chevy V6/V8 isn't cycling rich-lean often… Low P1154 Chevrolet · Powertrain On a Chevy V6/V8, the bank 2 front O2 sensor rises and falls at clearly different speeds. Low P1345 Chevrolet · Powertrain The cam signal is out of step with the crank signal; on Vortec engines usually a mis-set… Moderate P1380 Chevrolet · Powertrain A misfire was detected, and the ABS module couldn't supply rough-road data to confirm it wasn't… Moderate P1381 Chevrolet · Powertrain A misfire was detected while the PCM had lost contact with the ABS module that supplies… Moderate