Haldex 4 AOC (Active On-Demand Coupling) Differential Pump

If your AWD P3 Volvo has unexpectedly left you stranded in slippery conditions, it's possible your car's AWD needs service.

AWD Volvos from 2003 and up (like the S60R/V70R, XC70, XC90, and AWD versions of the S60/V70 and S40/V50) use a system called Haldex to engage the rear wheels when the front wheels start to slip.

A cutaway diagram of the Active On-Demand Coupling

This Haldex system relies on a multi-plate clutch in the rear of the car, also called the Active On-Demand Coupling (AOC). When the system detects front wheel spin, valves open and allow pressurized oil to clamp the clutch down, hooking up the rear wheels and getting you moving again.

The system relies on oil pressure as high as 80 bar (1100psi!) to cycle the hydraulic clutch, and just like any system that pumps oil around, regular filter and fluid changes are recommended. For Haldex, we suggest changing the fluid and filter every 50,000 miles

A clogged (and failed!) Haldex pump

If fluid changes are neglected and the filter gets clogged, the Haldex pump has to work harder and harder until it eventually burns out: you'll suddenly get lots of front wheel spin, and when scanned the car will have pump error codes from the DEM, such as DEM-0006.

This pump kit is made by the Original Equipment Manufacturer for Volvo for this part, BorgWarner. It includes a new pump and new allen bolts, and is perfect for getting all four of your P3's wheels spinning again.

Additional Keywords: AOC HALDEX DIFF DIFFERENTIAL