Powertrain, generic · Auxiliary emission controls

P0450 EVAP System Pressure Sensor/Switch A Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. The tank pressure sensor measures small pressures around ambient for the leak tests. Its direction differs by maker – on GM vacuum raises the voltage, on Ford and Bosch pressure does – so low and high refer to the signal voltage only. P0450 is the general circuit fault of tank pressure sensor A; makers that separate the fault use P0452 or P0453. Only Audi (2022/23) is documented with the code, as an electrical fault of the tank ventilation pressure sensor; GM, Ford and Saab do not use it. The leak tests are then suspended.

Likely causes

Connector at the tank pressure sensor corroded or loose (underbody, splash water)
Tank pressure sensor faulty
Damaged 5 V, ground or signal wire
Engine module software

Symptoms

  • Check engine light on
  • EVAP readiness not set, emission inspection not passed
  • No change in driving

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–250
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel tank pressure sensorsensor wiringengine control module

Related codes

P0451P0452P0453P0454P0455P0442

References: static.nhtsa.gov, law.cornell.edu, gsi.ext.gm.com.