Audi A4 - Bad or fluctuating idling behaviour | HELLA

If the defect mentioned above is discovered in combination with the fault codes described, a faulty oil trap (figure) in the crankcase ventilation at the cylinder head cover may be a possible cause.

There are pressure control and check valves installed in the oil trap housing. They regulate the suction of the blow-by gases according to the engine speed and the pressure ratio. An error in this area can cause speed fluctuations and a higher consumption of oil. In some cases, the vehicle switches off right after it is started.

Repair notes

The oil trap must be completely replaced in the event of damage as it cannot be disassembled or cleaned.

Please observe the repair notes issued by the relevant vehicle manufacturers in this context.