4C72 - P20B5 (DDE)

4C72 - P20B5

Information saved in
DDE

Fault code
4C72 - P20B5

Fault text
DDE: Reducing-agent pressure-line heating: Short circuit,
heater circuit

Fault description
Monitoring of reduction agent pressure line heating. The
diagnostic trouble code is logged when the measured current
draw from the deactivated heater exceeds the limit value
150 uA.

Condition for fault identification
Test condition:
The error check runs continuously when the urea tank heater
is deactivated.
Voltage condition:
The error check runs continuously when the urea tank heater
is deactivated.

Condition for fault memory entry
Debounce (15000 ms)

Action in service
1. Check the control wire and the diagnostic wire.
2. If wiring and plug connections are OK:
3. Check plug connections for moisture.
4. Use diagnostic system to test heating systems.
5. Replace power switch.

Fault effect and breakdown warning
-

Driver information
Warning light:
MIL

Service instruction
The power switch transmits an activation signal to all
heaters. The first heater circuit is for the active tank heater,
the second heater circuit is for the delivery module and the
metering line.
The control wire should not be in contact with ground or B+
when the DDE and power switch are unplugged.