Loss of power: Codes, Causes & Fixes

P0174 Powertrain The cylinder bank without cylinder 1 is running lean even with the maximum fuel correction… Moderate P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0420 Powertrain The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly. Low P0430 Powertrain The bank 2 converter on a V6, V8 or split-exhaust engine isn't cleaning the exhaust well enough. 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

P0206 Powertrain Injector 6's circuit is open or faulty. On an inline-six that's the rear cylinder, tucked under… Moderate P0207 Powertrain The ECU lost normal control of injector 7, which only exists on V8 and larger engines. Moderate P0208 Powertrain The circuit to injector 8, the rear cylinder on bank 2 of a V8, is open or doesn't respond… Moderate P0216 Powertrain The ECU can't control or confirm injection timing, usually on a diesel with an electronic… High P0217 Powertrain The engine overheated. Stop driving: continuing can warp the head, blow the head gasket… Critical P0221 Powertrain The second throttle angle signal leaves its window or stops following the plate, so power… Moderate P0231 Powertrain Voltage on the wire feeding the fuel pump is too low while the pump is supposed to be running. High P0234 Powertrain Boost rose above the safe limit the engine computer allows, so it may cut power to protect… High P0235 Powertrain The engine computer found an electrical fault in the boost pressure sensor's wiring… Moderate P0236 Powertrain The boost sensor's signal is electrically OK, but its readings don't make sense compared… Moderate P0237 Powertrain The boost sensor signal has dropped near zero volts, reading less pressure than the atmosphere… Moderate P0238 Powertrain The boost sensor signal is stuck near 5 volts, so the computer sees impossibly high boost… Moderate P0243 Powertrain The engine computer found a fault in the electrical circuit of the solenoid that controls… Moderate P0263 Powertrain Cylinder 1 is producing noticeably more or less power than the others, beyond what fuel trim… Moderate P0269 Powertrain Cylinder 3 isn't pulling its weight, or is pulling too hard, and the fuel correction for it… Moderate P0275 Powertrain The fuel correction for cylinder 5 is past its limit. Only engines with five or more cylinders… 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 P0301 Powertrain Cylinder 1 is repeatedly failing to fire. The cause is almost always its coil, plug, injector… Moderate P0302 Powertrain Cylinder 2 keeps misfiring. On inline engines it's a middle cylinder, so rule out coolant… Moderate P0303 Powertrain Cylinder 3 is misfiring. Check whether it misses at idle or under load before you blame… Moderate P0304 Powertrain Cylinder 4 is misfiring. Its end or rear position makes water, oil and intake leaks common… Moderate P0305 Powertrain Cylinder 5 is misfiring. First job: work out which bank it sits on, because that decides what… Moderate P0306 Powertrain Cylinder 6 is misfiring. On an inline-six it's the hot rear cylinder; on GM and Hemi V8s it can… Moderate P0307 Powertrain Cylinder 7 is misfiring. On GM and Hemi V8s it's a cylinder-deactivation cylinder, so check… Moderate P0308 Powertrain Cylinder 8 is misfiring. It's a rear V8 cylinder against the firewall, so its plug is often… Moderate P0321 Powertrain The rpm signal is there but erratic: extra or missing pulses the computer can't trust. Expect… Moderate P0336 Powertrain Crank signal present but implausible: damaged teeth, a slipped balancer ring or debris confuse… Moderate P0340 Powertrain The computer lost the camshaft signal on bank 1. Expect long cranking, less power… Moderate P0341 Powertrain The bank 1 cam signal lands at the wrong crank angle, often from a stretched chain or a sticky… Moderate