Powertrain, generic · Auxiliary emission controls

P0454 EVAP System Pressure Sensor/Switch A Circuit Intermittent

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
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. P0454 means the signal jumps. Ford checks continuously for a jump above about 1 kPa between two samples 100 ms apart or a brief open or short. GM (and the Saab 9-4X) checks only during the engine-off leak test: a jump of about 112 Pa within 1 s that refuelling cannot explain, 2 of 3 tests, MIL on the first trip. Saab's ME9 does not use the code. The engine-off small-leak test is then discarded.

Likely causes

Loose contact at the connector to the tank pressure sensor
Chafed harness at the tank
Sensor faulty internally (noisy signal)
Fuel sloshing in an overfilled tank or refuelling misdetected

Symptoms

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

Repair estimate

DifficultyMediumDIY possible
Parts and labour€20–250
Time0.5–3 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

P0450P0451P0452P0453P0442P0461

References: gsi.ext.gm.com, newtonnet.co.uk, saabwisonline.com, static.nhtsa.gov.