VOLVO
DEM-P188974 - Oil Pressure Pump Performance. Mechanical Failures. Actuator slipping
System
Differential Electronic Module (DEM)
Volvo models this fault code applies to
Applies to the following models:
4 modelsS80 (2007–), V70 (2008–), XC70 (2008–), XC90 (2003–)
Show models by year and engine (6)
What does this fault code mean?
The four-wheel drive control module (DEM) measures the oil pressure in the Haldex clutch (AOC) through a pressure sensor. When engine speed rises, an electric feed pump should build a base pressure in the clutch. If that pressure is not reached in time, the code is set and the four-wheel drive can be disengaged. The cause may be the sensor, the pump, too little oil in the clutch or an internal leak.
Possible causes
- Pressure sensor not functioning
- Damaged feed pump
- Too little oil in the clutch
- Internal leak in the clutch
What you can do
- 1Read off the fault code and note whether it is permanent or has gone. If it has gone, no action is needed
- 2Look for oil leaks at the clutch and the rear axle
- 3Check the connector to the control module and the wiring to the feed pump for oxidation, loose connections and damage
- 4If you have a diagnostic tool, read the oil pressure in live data as engine speed rises and check that the pressure climbs promptly
- 5Listen for unusual noises from the clutch and the rear axle during a test drive
- 6If the fault remains, have a workshop check the clutch (AOC) and replace the feed pump or pressure sensor as needed
Symptoms you may notice1
- Four-wheel drive does not work
What the fault can affect1
- Four-wheel drive is disengaged
General guidance for car owners. Diagnosis on the car can point to a different cause.