Loss of power: 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 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

P0409 Powertrain The ECM lost a usable signal from the EGR position or pressure sensor – often an open… Low P0420 Powertrain The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly. Low P0421 Powertrain The close-coupled warm-up catalyst on bank 1, right behind the exhaust manifold, isn't working… Low P0422 Powertrain The main underfloor catalytic converter on bank 1 no longer stores enough oxygen to pass… Low P0430 Powertrain The bank 2 converter on a V6, V8 or split-exhaust engine isn't cleaning the exhaust well enough. Low P0431 Powertrain On a V6, V8 or flat engine, the warm-up converter on the side without cylinder #1 is no longer… Low P0471 Powertrain The exhaust backpressure reading doesn't match what the computer expects; the sensor tube… Moderate P0472 Powertrain Exhaust backpressure sensor signal near zero volts: dead sensor, grounded wire or lost 5 V… Moderate P0524 Powertrain Measured oil pressure fell below the safe minimum. Stop the engine now and check the oil before… Critical P0573 Powertrain The PCM thinks the brake pedal is always pressed – brake lights stay on, often from a missing… Moderate P0607 Powertrain A general internal performance check in the engine computer failed – supply, grounds… Moderate P061B Powertrain The ECM's safety monitor disagreed with its own engine torque calculation – often bad input… Moderate P0642 Powertrain The PCM's 5-volt supply 'A' is being pulled below spec, usually by a short to ground in one… High P0651 Powertrain The PCM's second 5-volt sensor supply is out of range – usually a pedal, throttle or pressure… Moderate P069E Chevrolet · Powertrain The fuel pump control module stored its own fault and asked the engine computer for the check… 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 P0733 Powertrain Third gear slips: input shaft speed doesn't match output speed times the 3rd-gear ratio. Moderate P0751 Powertrain Solenoid A is wired fine but its valve isn't doing its job, so gears are missing – often stuck… High P0756 Powertrain Solenoid B isn't moving fluid the way the TCM expects – the car may pull away in 3rd or 4th. High P0868 Powertrain Measured transmission line pressure is below what the TCM commanded – clutches can slip… High P0894 Powertrain The transmission computer measured slip inside the gearbox that shouldn't be there. Clutches… High 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 P0A7E Powertrain The high-voltage battery got too hot. A clogged cooling intake or dirty fan is the usual cause. Moderate P0A7F Powertrain The battery computer has calculated that the whole high-voltage pack has worn past its usable… Moderate P0A80 Powertrain The hybrid system sees weak or unbalanced modules in the high-voltage battery and flags… Moderate P0A93 Powertrain The inverter's separate coolant loop isn't carrying heat away – usually a dead electric… High P0A94 Powertrain A hybrid voltage converter isn't delivering the voltage it should – on Toyotas, the boost… High P0A95 Powertrain The main fuse in the high-voltage battery circuit has opened or its circuit reads open… Critical