Check engine light on: Codes, Causes & 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 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 P0135 Powertrain The heater inside the upstream oxygen sensor on bank 1 isn't working or its circuit is faulty. Low P0171 Powertrain The engine computer is adding the maximum extra fuel it's allowed on bank 1 and still sees… 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 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 P0742 Powertrain The converter lockup clutch stays applied when it should be released, which can stall… High P0743 Powertrain The TCC solenoid circuit shows an electrical fault such as a short, overcurrent or out-of-range… Low 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 P0841 Powertrain Pressure sensor or switch A reports a value that doesn't fit the gear or pressure the TCM… Moderate P0851 Powertrain The engine computer sees the park/neutral input stuck at low voltage, often from a short… Low P0852 Powertrain The park/neutral input reads too high, usually from an open circuit, unplugged connector or bad… Low P0868 Powertrain Measured transmission line pressure is below what the TCM commanded – clutches can slip… High P0884 Powertrain The transmission computer's power supply dropped out briefly – usually a battery, ground… Moderate P0887 Powertrain The circuit that switches the transmission power relay reads high voltage when it shouldn't. Moderate P0894 Powertrain The transmission computer measured slip inside the gearbox that shouldn't be there. Clutches… High P090C Ford · Powertrain The PowerShift TCM sees a low signal on the motor that works clutch B, the even-gear… Moderate P0A0F Powertrain The hybrid system spun the gas engine with its motor-generator to start it, but the engine… High P0A1F Powertrain The module that manages the high-voltage battery failed its self-check or reports implausible… Moderate