Powertrain, generic · Auxiliary emission controls

P0453 EVAP System Pressure Sensor/Switch A Circuit High

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. P0453 means its signal voltage is above the upper limit: GM above 4.85 V (640 of 800 samples, MIL after two trips), Ford and Saab 9-4X above 4.9 V for 5 s. Ford states explicitly that an open circuit sets P0453, because the module's pull-up then drives the signal high. Other causes are a short to 5 V or battery voltage. Leak tests are then suspended.

Likely causes

Signal or ground wire open, connector off
Tank pressure sensor faulty
Signal shorted to 5 V or battery voltage
Engine module

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

P0450P0451P0452P0454P0455P0643

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