The brief
The CLA180 came in for routine servicing, and the inspection caught two jobs: the engine mounts had sagged, which is the vibration coming through the cabin, and the oil control valve was faulty, the valve that manages the oil flow the engine relies on for lubrication. The owner had both done in the one visit. The engine and gearbox sit on rubber mounts that hold their weight and absorb the shake, and as the rubber ages it sags and the drivetrain starts moving around, so the vibration comes straight through. The oil control valve regulates oil pressure and flow so the moving parts get a steady supply, and when it fails the flow fluctuates, which over time wears the engine. Both are things you don't leave once the inspection's flagged them, so it was the mount set and the oil valve, done with the service.
The diagnosis
The inspection and a diagnostic check went through everything. On the lift the engine and gearbox mounts had sunk with cracked rubber, the play obvious under load; and the diagnostics and an oil pressure check showed the oil control valve wasn't regulating cleanly, the flow fluctuating where it should hold steady. The oil and filters and a couple of fluids were due too. So it was a service plus a mount set plus an oil control valve: the wear items refreshed, fresh mounts holding the drivetrain, a fresh valve managing the oil flow.
The work
The engine oil and filter were changed and the other service items done. On the lift the engine and gearbox were taken onto transmission jacks, the worn mounts removed, and new genuine Mercedes-spec mounts fitted across the set, every fastener torqued and the drivetrain checked sitting square. The faulty oil control valve was removed and a new genuine Mercedes valve fitted with a fresh seal, then the oil pressure checked across idle and load to confirm it was holding steady, and the stored codes cleared. A road test confirmed a steady idle, no vibration, no oil pressure flag, and steady running.
The outcome
Smooth at idle, no vibration through the cabin, steady oil pressure with the flow back in control, fresh oil and filters, and a clean scan. The CLA180 went home serviced and sorted. Worn mounts and a faulty oil valve are exactly the things the inspection is for, so catching them and renewing both while the car was in kept them from becoming bigger problems.