On four wheel drive cars the oil and filter of the Haldex clutch are wear items and have to be replaced, and that service is the one most often skipped. If it is skipped, the rear axle engages erratically, it clicks in corners, and eventually the clutch and the pre-charge pump fail. The pump is the expensive part.
What to check
- Ask about the Haldex oil and filter change, and ask for the invoice
- On the test drive, manoeuvring slowly in a tight corner, listen for clicking
- Look from below for oil traces around the rear differential and the Haldex unit