Fuel vapour leaks
Fuel vapour leaks and the pressure sensor that finds them. The car tests the tank for tightness itself — it seals the system and watches the pressure. If it does not add up, a leak code appears, and its size is in the name of the code: large, small or very small.
7 codes in this section, 7 with a guide
What it usually turns out to be
- A large leak is almost always the fuel cap. Start there, not with a smoke machine.
- A very small leak is found with smoke in a workshop: such a crack cannot be seen by eye.
- The self-test only runs at a certain tank level — it will not start with an empty or a full tank.
P0450Fuel vapour pressure sensor — malfunctionguideP0451Fuel vapour pressure sensor — reading out of rangeguideP0452Fuel vapour pressure sensor — low signalguideP0453Fuel vapour pressure sensor — high signalguideP0455Evaporative emission system leak detected (gross leak)guideP0456Evaporative emission system leak detected (very small leak)guideP0457Evaporative leak — fuel cap left looseguide
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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 4Canister and purge valves 9Fuel 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