Fluid Leaks

• Whenever you have a fluid leak, it's a good sign there's something wrong with your engine. If you notice a fluid leak either during driving or after you park the car examine the Haldex controller unit. If the fluid isn't coming from the unit, then be sure that the unit hasn't been damaged by the dripping fluid either. If the fluid appears to bypass the controller unit entirely, you should still check to see where it is coming from.
  
  

Performance Issues

• If you notice problems during shifting, they could be related to your Haldex controller. Turn on the engine and drive in a slow, tight circle at roughly 10 miles an hour. Disengage the clutch and close the throttle. Do this a second time, but rather than closing the throttle rev it up to between 3,000 and 4,000 rpm. The second case should take you half the stopping distance if the unit is working properly, and if not then you should have it investigated.
  
  

Warning Lights

• If there's a problem with your Haldex unit your car's computer should pick up it and turn on the warning lights. These lights go off when your car is experiencing problems even if you can't readily tell what the problems are. So even if you can't feel a change in the performance, take the car to a mechanic to have the warning light issue cleared up before driving more than necessary.
  
  

Noises

• While it is a computerized unit, rattling noises might be an issue if your Haldex controller isn't installed properly or fully. Check the wires leading in and out of the unit, and check the unit itself to make sure it doesn't bounce or jostle easily. If the unit is loose, or the cables are rattling, adjustments need to be made to solve the issue.