Discovery II
EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-21
If the purge valve breaks or becomes stuck in the open or closed position, the EVAP system will cease to function
and there are no default measures available. The ECM will store the fault in memory and illuminate the MIL warning
lamp if the correct monitoring conditions have been achieved (i.e. valve status unchanged for 45 seconds after engine
has been running for 15 minutes). If the purge valve is stuck in the open position, a rich air:fuel mixture is likely to
result at the intake manifold, this could cause the engine to misfire and the fuelling adaptions will change.
The following failure modes are possible:
l
Sticking valve
l
Valve blocked
l
Connector or harness wiring fault (open or short circuit)
l
Valve stuck open
If the purge valve malfunctions, the following fault codes may be stored in the ECM diagnostic memory, which can be
retrieved using TestBook/T4:
Canister Vent Solenoid (CVS) Unit – (NAS with vacuum type, fuel evaporation leak detection system only)
1 CVS unit
2 Mounting bracket
3 Spring clips to pipe from EVAP canister
4 Harness connector
The canister vent solenoid (CVS) valve is mounted on a slide-on bracket which is riveted to the cruise control bracket
at the right hand side of the engine compartment. The vent pipe from the EVAP canister is connected to a stub pipe
on the CVS unit via a hose and plastic pipe combination. A two-pin connector links to the engine management ECM
via the engine harness for solenoid control; one of the wires is the supply feed from fuse No.2 in the engine
compartment fusebox, the other wire is the valve drive line to the ECM. The solenoid is operated when the ECM
grounds the circuit.
P-code
Description
P0440
Purge valve not sealing
P0444
Purge valve open circuit
P0445
Purge valve short circuit to ground
P0443
Purge valve short circuit to battery voltage
