P0128

1D2008 - P0128

Information saved in
DME

Fault code
1D2008 - P0128

Fault text
Map thermostat, mechanical: jammed open

Fault description
The diagnostic function monitors the rise in engine
temperature (coolant temperature at engine discharge
fitting).

Condition for fault identification
Test condition:
A fault is recognized when the engine temperature is below
81 °C when the test is executed. Because the test time is
defined by the temperature model, it is also determined by
the model's input variables (air mass, ambient temperature).
Potential problem source(s):
- Defect in wiring harness
- Characteristic map thermostat defective
Terminal condition: none
Voltage condition:
- Electrical system voltage > 10 V
Temperature condition:
- Ambient temperature > -10 °C
- Engine temperature at start > -10 °C and < 60 °C
- Boost-air temperature > -10 °C
Time condition:
- None
Other conditions:
- Engine on

Condition for fault memory entry
This fault is logged in the control module's fault memory if
it remains present for longer than 20 sec.

Action in service
- Check wiring harness for short to ground
- Replace map-controlled thermostat

Fault effect and breakdown warning
Breakdown notice:
- none
Possible apparent symptoms:
- The output of the interior heater may be reduced.

Driver information
Warning light:
- ECE emissions warning lamp: off
- US emissions warning lamp: on
- ECE electronic engine power reduction: off
- US electronic engine power reduction: off
- CC message: none

Service instruction
- When the engine is heated from external sources, such as
an auxiliary heater, diagnosis errors can result