What Haldex actually is
On many Audi and VW 4WD cars the engine sits sideways. Drive goes to the front, and a Haldex coupling sits in the rear diff. When the fronts slip, the pump locks the coupling and sends torque rearwards.
That is not the same as a Torsen centre-diff quattro on a longitudinal Audi. If someone says “all quattro is the same”, they are mixing systems.
Which cars typically need one
Common examples. Always confirm on the VIN, not the badge.
- Audi A3 / S3 / RS3 quattro (transverse)
- Audi TT quattro, many Q3 quattro
- Volkswagen Golf 4Motion and Golf R
- Tiguan 4Motion, and other transverse 4Motion models
Symptoms of a Haldex that is overdue or failing
A failed pump is a bigger bill than a service. The filter blocking is usually how it starts.
- Car feels front-wheel drive in the wet
- Pump running on after you switch off, or a whine from the rear
- 4WD warning on the dash
- Clunk from the rear on take-off
What the service involves
Drain the coupling, replace the filter (generation dependent), refill with the specified Haldex fluid. Some generations also need a pump screen clean.
Book it with a DSG service if both are due. See gearbox servicing for the work, and the servicing page for how we quote.