DTC P1444

DTC: P1444 Purge flow switchover valve without function (functional response)

Activation requirement CHECK ENGINE lamp:
After two consecutively "performed" tests with fault.

Activation of CHECK ENGINE lamp:
At start of next trip.

Test to detect fault:
To actuate the logic chain, the following conditions must be met simultaneously:
^ Purge control valve (Y58/1) closed
^ No deceleration fuel shut-off
^ Momentary intake air temperature > + 10 °C
^ Evaporation ratio not in 40 - 60% range.

The diagnostic module subsequently activates the purge flow switchover valve (Y27/6). The diagnostic module pressure sensor (B5/2) thereby detects the barometric pressure via the charcoal canister.

This barometric pressure is compared with the intake manifold pressure values which are measured during deceleration. The barometric pressure must be higher by more than approximately 250 mbar, otherwise a fault is present in the switchover function.