The brief
The A5 was at its scheduled service interval. No faults, no warning lights, just the owner keeping ahead of the maintenance schedule.
Two consumable intervals happened to line up at this visit. The car had crossed 60,000 km, which is the spark plug interval, and the battery was three years old, the point at which the original starts to fade. So this was not just an oil-and-filter: it was the chance to refresh several things at once while the car was already in the bay.
The owner asked for the works: oil and filter, a proper inspection, and whatever the schedule called for so nothing was creeping toward a failure.
The diagnosis
A battery load test showed the original unit at end of life. Voltage dropped under a cranking simulation further than the healthy band allows, and the recovery curve afterwards was slow, which together say the battery can no longer carry the modern electrical load reliably. Due for replacement.
The spark plugs, pulled for a look, showed the electrode wear you would expect at 60,000 km, right in line with the recommended interval. The air filter was dirty enough to be worth doing while the airbox was open. The diagnostic scan came back clean, no stored fault codes anywhere. Belts, hoses and suspension all in spec.
So the scope was: oil and filter, spark plug set, air filter, and a new battery.
The work
Drained and refilled the engine oil with the correct VAG long-life spec, fitted a new oil filter.
Replaced all four spark plugs with new VAG-spec units, each gapped to the workshop manual figure and torqued in carefully. Swapped the air filter while the airbox was open.
Fitted a new VAG-spec AGM battery and, importantly, registered it on the scanner. The charging system on this car adjusts its profile to the battery's age and state, so a new battery has to be registered or the car keeps charging it as if it were the old worn one, which shortens its life. That registration step is the bit a quick battery swap usually skips.
Reset the service interval indicator.
The outcome
Idle smoothed out on the new plugs, the engine running clean. Normal cranking from the fresh battery. Clean diagnostic scan after the work.
The A5 went home reset for another long stretch, with the service log signed off and the next interval noted. For the owner, this is what a proper service looks like: not just the oil, but the plugs, the filter and the battery all refreshed at the point the schedule called for them, so the car keeps running the way it should and there are no surprises down the road.
The kind of maintenance record that also holds the car's value at trade-in time.
