4D20

4D20 - P20A5

Information saved in
DDE

Fault code
4D20 - P20A5

Fault text
DDE: Reducing-agent changeover valve, plausibility:
Changeover valve jammed closed

Fault description
Plausibility check on 4/2 directional-control valve (switch
valve) in delivery module. Once compliance with the test
conditions is present the current pressure of the reduction
agent is saved. When the state machine enables the test the
pressure differential between the saved pressure value and
the current monitored value is calculated and monitored for
the limit value 1000 mbar. If the limit value is exceeded this
indicates a sticking reversing valve and a diagnostic trouble
code is logged.

Condition for fault identification
Test condition:
The error check proceeds when the state machine has the
value COSCR_PRESSUREREREDUCTION and the
pressure of the delivery module is above the limit value
3000 mbar.
Voltage condition:
The error check proceeds when the state machine has the
value COSCR_PRESSUREREREDUCTION and the
pressure of the delivery module is above the limit value
3000 mbar.

Condition for fault memory entry
Event debounced (1)

Action in service
1. Use the diagnostic system to activate the suction valve.
2. Replace delivery module.

Fault effect and breakdown warning
-

Driver information
Warning light:
MIL

Service instruction
none