Canister and purge valves
The charcoal canister and its valves: the system that catches petrol vapour from the tank and sends it into the engine instead of the atmosphere. The purge valve and the vent valve live here — two parts that stick more often than they fail.
9 codes in this section, 9 with a guide
What it usually turns out to be
- A stuck purge valve gives hunting idle and a smell of petrol in the cabin.
- An «incorrect purge flow» code is about the flow, not about the valve electrics.
- The check almost always starts at the fuel cap: ten seconds and no money.
P0440Evaporative emission system — malfunctionguideP0441Evaporative emission system purge flow faultguideP0442Evaporative emission system leak detected (small leak)guideP0443Evaporative emission purge control valve circuit malfunctionguideP0444Canister purge valve — open circuitguideP0446Canister vent valve — circuit malfunctionguideP0447Canister vent valve — open circuitguideP0448Canister vent valve — circuit shortedguideP0449Canister vent valve — control malfunctionguide
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Other sections
Fuel and air metering, general 33Intake measuring sensors 17Oxygen sensors 19Throttle and accelerator pedal 15Mixture: lean and rich 11Fuel and air metering: injectors 25Ignition system and misfires 29Exhaust gas recirculation (EGR) 7Secondary air injection 3Catalytic converter 4Fuel vapour leaks 7Fuel level in the tank 4Diesel particulate filter 6Idle and auxiliary systems 22Control module and its circuits 21Transmission 17Communication between modules 20Brakes, ABS and stability control 17Body, airbags and lighting 12