20A902

20A902 - P15D5

Information saved in
DME

Fault code
20A902 - P15D5

Fault text
Coolant pump, operation with reduced output: Undervoltage
detected

Fault description
The diagnostic function monitors the power-supply voltage
to the electric water pump.

Condition for fault identification
Test condition:
The fault is recognized when the voltage is <10 V.
Potential problem source(s):
- Battery charge status or electrical system voltage is not OK
- Defective wiring harness
- Defective water pump
Terminal condition: none
Voltage condition:
- Onboard electrical system voltage between 9 V and 16 V
Temperature condition:
- None
Time condition:
- None
Other conditions:
- Engine on
- No BSD fault
- No alternator fault

Condition for fault memory entry
The diagnostic fault code is logged when the fault remains
present for longer than 1 min.

Action in service
- Continue test routine with test modules that deal with
problems related to voltage in onboard electrical system
- Start engine, set heat to maximum output, allow to run for
one minute and the check to determine whether the
diagnostic fault code has been logged again
- If the fault continues to appear despite correct electrical
system voltage replace the water pump

Fault effect and breakdown warning
Breakdown notice:
None
Possible apparent symptoms:
CC message if engine becomes too hot, breakdown in
extreme cases

Driver information
Warning light:
- ECE emissions warning lamp: off
- ECE electronic engine power reduction: off
- CC message: on
- US emissions warning lamp: off
- US electronic engine power reduction: off
- CC message: on

Service instruction
Observe sequence for fault rectification:
- If the pump is activated at TMOT>90 °C as tester job the
diagnostic fault code 0x3792 or 0x20AD08 'Water pump:
rotation speed implausible' can be logged, ignore this fault
and delete it --> Carry out tester job at Tmot<90 °C