Diagnostic guide
What the problem can involve
crankcase ventilation / air-oil separator faults.
Symptoms owners may notice
smoke, rough idle, high crankcase vacuum or oil ingestion.
Important: AOS symptoms can overlap with other vacuum, ignition or engine faults.
How we approach diagnosis
We start by confirming the symptom and vehicle details. Depending on the fault, the next step can include scan data, road testing, pressure testing, electrical measurement, smoke testing, mechanical inspection or fluid assessment. The aim is to separate the cause from the symptom before parts are ordered.
What happens after diagnosis
Once the fault is confirmed, we explain the repair path, any related maintenance items and what should be rechecked after the repair.