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OBD2 code guides

You have a code. Start making sense of it.

Find an explanation you can use: what the vehicle reported, what remains uncertain and how to prepare the next conversation with your mechanic.

50 codes explained · 16 topics · English & Spanish

50 guides found

Fuel mixture

P0171System too lean — bank 1 P0172System too rich — bank 1 P0174System too lean — bank 2 P0175System too rich — bank 2

Misfires

P0300Random or multiple cylinder misfire detected P0301Cylinder 1 misfire detected P0302Misfire detected in cylinder 2 P0303Misfire detected in cylinder 3 P0304Misfire detected in cylinder 4 P0305Combustion irregularity detected in cylinder 5 P0306Combustion irregularity detected in cylinder 6 P0307Combustion irregularity detected in cylinder 7 P0308Combustion irregularity detected in cylinder 8

Catalyst efficiency

P0420Catalyst efficiency below threshold — bank 1 P0430Catalyst efficiency below threshold — bank 2

EVAP & fuel vapors

P0441EVAP purge flow does not match expectations P0442EVAP monitor indicates a small leak P0446EVAP vent control fault P0455EVAP large leak / no-flow result P0456EVAP monitor indicates a very small leak

Air intake & sensors

P0101Airflow sensor A — range or performance P0102Airflow sensor A — low circuit input P0103Airflow sensor A — high circuit input P0106MAP / barometric pressure — range or performance P0113Intake air temperature sensor 1 — high input

Coolant & temperature

P0117Coolant temperature sensor 1 — low input P0128Coolant below thermostat regulating temperature

Oxygen sensors

P0130Oxygen sensor circuit — bank 1, sensor 1 P0133Slow oxygen-sensor response — bank 1, sensor 1 P0135Oxygen-sensor heater — bank 1, sensor 1 P0141Oxygen-sensor heater — bank 1, sensor 2

Variable valve timing

P0011Camshaft A timing too advanced — bank 1 P0014Camshaft B timing too advanced — bank 1

Crank & cam signals

P0335Crankshaft position sensor A circuit P0340Camshaft position sensor A circuit — bank 1

Idle control

P0507Idle speed higher than expected

Turbo & boost

P0234Turbo or supercharger — excessive boost P0299Turbo or supercharger — boost below target

EGR recirculation

P0401EGR — recirculated flow below expectation P0402EGR — recirculated flow above expectation

Electronic throttle

P0121Throttle/pedal signal A — implausible range or response P0122Throttle/pedal signal A — low electrical input P2135Throttle/pedal position — A and B signals disagree

Electrical supply

P0562System supply voltage too low P0563System supply voltage too high

Fuel pressure

P0087Fuel rail or system pressure below requirement P0191Fuel-rail pressure signal — range or performance

Automatic transmission

P0700Transmission control system — fault warning request P0715Transmission input/turbine speed signal A — circuit fault P0741Torque-converter lockup — performance or failure to engage

A code that is not listed has not been assessed here; its absence does not mean your vehicle is fault-free.