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 B0001 Body The airbag module found a fault in the firing circuit for the driver's front airbag (stage 1). High P0171 Powertrain The engine computer is adding the maximum extra fuel it's allowed on bank 1 and still sees… Moderate P0420 Powertrain The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly. Low P0128 Powertrain The engine takes too long to warm up, which almost always points to a thermostat stuck open. Low

P0715 Powertrain The transmission computer has lost a reliable input-shaft speed signal, so shifts get harsh… Moderate P0716 Powertrain The input speed signal is there but erratic or illogical – dropouts, spikes or values that… Moderate P0717 Powertrain The input speed sensor reports zero while the engine runs and the car moves – the signal… Moderate P0720 Powertrain Electrical fault in the output shaft speed signal – shift timing and sometimes the speedometer… Moderate P0722 Powertrain The output speed sensor sends nothing while the car moves – shifting and often the speedometer… Moderate P0730 Powertrain The transmission computer sees input and output shaft speeds that don't fit the gear it… High P0731 Powertrain While in first gear, the transmission's input and output speeds don't match the first-gear… Moderate P0732 Powertrain Second gear isn't holding: the input-to-output speed ratio in 2nd is outside the expected range. Moderate P0733 Powertrain Third gear slips: input shaft speed doesn't match output speed times the 3rd-gear ratio. Moderate P0734 Powertrain Fourth gear (overdrive on four-speed units) doesn't hold the expected input-to-output speed… Moderate P0735 Powertrain Fifth gear slips or isn't fully applied; the TCM measures a ratio that doesn't fit 5th. Moderate P0741 Powertrain The torque converter lockup clutch slips or won't engage when the computer commands it. Moderate P0742 Powertrain The converter lockup clutch stays applied when it should be released, which can stall… High P0744 Powertrain Lockup control drops in and out: an intermittent TCC circuit, or on some makes a lockup… Moderate P0746 Powertrain Solenoid A doesn't control pressure as commanded: harsh or soft shifts, or limp mode. 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 P0755 Powertrain The TCM detects an electrical problem with shift solenoid B, the second on/off shift valve. Moderate P0756 Powertrain Solenoid B isn't moving fluid the way the TCM expects – the car may pull away in 3rd or 4th. High P0760 Powertrain A fault in shift solenoid C's circuit – usually means lost overdrive or upper gears, or limp… Moderate P0770 Powertrain Solenoid E in a five- or six-speed automatic isn't working as commanded: electrical fault… Moderate P0773 Powertrain The transmission computer found an open, short or wrong current in the solenoid E circuit… Moderate P0776 Powertrain Pressure control solenoid B isn't delivering the pressure the TCM asks for – harsh or slipping… Moderate P0780 Powertrain A gear change didn't complete the way the TCM expected, but it can't pin the fault to one part. Moderate P0781 Powertrain The upshift from 1st to 2nd is too slow, slips or never completes properly. Moderate P07A3 Ford · Powertrain The PowerShift's odd-gear clutch isn't letting go when the TCM commands it open, so the car… High P0841 Powertrain Pressure sensor or switch A reports a value that doesn't fit the gear or pressure the TCM… Moderate P0868 Powertrain Measured transmission line pressure is below what the TCM commanded – clutches can slip… High