The brief
The A4 came in for its Audi Care service, the owner keeping it on schedule, and the inspection that goes with it turned up two jobs worth doing while it was on the ramp: the front upper control arms were worn, and the engine air filter was clogged. He had both done in the one visit, which is the efficient way. The upper control arms locate the top of the front suspension, with ball joints and bushings that keep the geometry precise and the front end quiet, and when they wear there's play, so you get a knock over bumps, looser steering and uneven tyre wear. The air filter cleans the air going into the engine, and a clogged one chokes the intake and lets fine particles through. Neither gets better on its own, so it was the service plus a pair of upper control arms and a fresh air filter, with the alignment reset.
The diagnosis
The inspection went through everything. On the lift the front upper control arms on both sides had play in their ball joints and bushings, the cause of the knock and the vagueness; the air filter was loaded with the dirt it had caught, restricting the intake. The oil and a couple of fluids were due too. No other faults flagged. So it was a service plus an upper control arm pair and the air filter: the wear items refreshed, fresh arms holding the geometry, a clean filter for the engine.
The work
The engine oil and filter were changed and the fluids topped. On the lift both front upper control arms were unbolted and removed, and a new genuine Audi pair fitted with fresh ball joints and bushings, every fastener torqued to the manual figures, and the air filter replaced with a new genuine unit, the airbox cleaned out before it closed up. The car went on the alignment rig and the front geometry set to specification. A road test confirmed the knock was gone, the steering tight, the engine breathing cleanly, and nothing leaking.
The outcome
No more knock over bumps, tight steering on fresh upper control arms, clean air to the engine, the alignment set so the front tyres wear evenly, and the service done alongside it. The A4 went home sorted in one visit. The upper control arms and the air filter were exactly the things the inspection is for, so catching them and renewing them with genuine parts while the car was in kept them from becoming separate trips.
