Audi A5 (8T) Common Problems: What to Check Before You Buy

The 8T-generation Audi A5 is a comfortable, solidly built long-distance car that is let down by a short list of well-documented faults rather than by general fragility. The headline items are timing chain tensioner and guide wear on the chain-driven engines, oil consumption on earlier 2.0 TFSI petrols, injector and EGR/DPF trouble on the 2.0 TDI, the Multitronic CVT fitted to front-wheel-drive automatics, worn front upper control arm bushes, and water finding its way into footwells, boots and Cabriolet roof drains. None of that makes it a bad car — a maintained example with the right engine and gearbox is a genuinely good thing to own — but which specific car you buy matters far more here than which model.

Timing: which engines use a chain and which use a belt

This is the single most important thing to get straight, because it varies by engine code, not by year.

The 1.8 and 2.0 TFSI four-cylinders (the EA888 family) are chain-driven, with the chain at the gearbox end of the engine. Earlier examples are known for tensioner wear that lets the chain slap and, in the worst case, jump timing — which damages the engine. The classic warning is a brief rattle in the first second or two after a cold start, often alongside crankshaft/camshaft correlation fault codes. A revised tensioner design exists; ask for evidence it has been fitted.

The 3.2 FSI V6 (naturally aspirated, pre-facelift), the 4.2 FSI V8 in the pre-facelift S5 and in the RS5, and the supercharged 3.0 TFSI V6 are all chain-driven too, with the chains at the back of the engine. On those, chain and guide work is a major job because access usually means removing the engine or gearbox. The V6 diesels — the 2.7 TDI and the 3.0 TDI — are chain-driven at the rear as well, and chain stretch is a known concern on high-mileage cars.

The 2.0 TDI is the exception: it uses a timing belt. Every 2.0 TDI in this car is common-rail — the older PD injection units did not carry over into this generation. This is an engine where a snapped belt means serious internal damage, not a roadside repair, so the belt and water pump are a genuine deadline rather than an advisory. Intervals were revised more than once over the years, so check the car's actual service schedule and paperwork rather than assuming a figure, and treat an unproven belt history as a cost you will be paying immediately.

TFSI petrol engines: oil consumption, carbon and cooling

The earlier 2.0 TFSI engines in this car have a genuine reputation for high oil consumption, traced to the piston and oil-control ring design. Revised pistons were fitted to later engines and to some repaired ones. Check the oil level yourself on a cold car, and treat a low level with no top-up receipts as a warning rather than an oversight — a chain tensioner is one of the things that suffers when the level is allowed to drop.

Direct injection means petrol never washes over the back of the intake valves, so carbon deposits build up over time. Symptoms are a lumpy cold idle, misfires and flat part-throttle response. It is a cleaning job (usually media or walnut blasting) rather than a failure, but it is a real running cost.

Two smaller items turn up repeatedly on these engines: the crankcase breather / PCV diaphragm splits, giving a lean running code, rough idle and sometimes an audible whistle; and the plastic thermostat housing and water pump seep coolant. Look for dried pink or white crust around the front of the engine and check the coolant level and the expansion tank.

The 3.0 TFSI V6 is a different animal — supercharged, not turbocharged. It also builds carbon, and its cooling components are worth a careful look for weeps and stains.

Diesels: injectors, EGR, DPF and the emissions work

On the 2.0 TDI, the common-rail injectors are the known weak point on earlier cars. A leaking or failing injector shows up as a hard cold start, a diesel knock that is louder on one cylinder, smoke, or fuel finding its way into the engine oil (a rising oil level is a serious sign). Cylinder-specific injector faults or low rail pressure codes point the same way.

EGR valves and coolers clog with soot, and the DPF is only as happy as the car's use pattern: a diesel A5 used only for short urban trips will struggle to complete regenerations, which eventually means a blocked filter and oil dilution. Ask how the car has been driven. Glow plugs and, on higher-output versions, the electronic turbo actuator are also common.

The 2.0 TDI's intake manifold flap actuator is a well-known failure on this generation and sets a manifold runner position fault. The V6 diesels — 2.7 and 3.0 TDI — have their own swirl-flap actuator motors that fail in a similar way, plus oil cooler and EGR cooler leaks.

Many 2.0 TDI cars of this generation fall under the manufacturer's diesel emissions service action in the markets where it ran. Rather than assuming, check whether this particular car was affected, whether the work was carried out, and that there is a record of it — and be aware that some owners report EGR and DPF niggles afterwards.

On manual diesels, listen for a dual-mass flywheel rattle at idle with the clutch pedal up.

Gearboxes: Multitronic, tiptronic and S tronic

The A5 was sold with three quite different automatics, and they are not interchangeable in reputation. Front-wheel-drive cars were also available with a manual, which is a different proposition entirely — so establish what is actually in the car in front of you.

Front-wheel-drive automatics used the Multitronic CVT. It is the one to inspect hardest. Symptoms of trouble are shunt or judder pulling away from rest, slipping under load, harsh or delayed engagement, or the car dropping into a limp mode. Repair costs can approach the value of an older car. A well-kept one with fluid service history and a smooth, seamless drive can be fine, but there is no cheap fix if it is not.

Quattro cars with the conventional torque-converter tiptronic — six speeds, with an eight-speed on some later cars — have the least troublesome reputation of the three, though they still want their fluid changed rather than being treated as sealed for life.

The seven-speed S tronic dual-clutch is a wet-clutch unit, fitted to quattro models from around 2010 onwards; it was the only gearbox the RS5 was offered with, and the facelift S5 used it too. The known issue is the mechatronic control unit, along with clutch shudder. On the test drive, pay close attention to crawling speeds, stop-start traffic and hill starts — hesitation, jerking or a flare of revs between gears is where a tired unit shows itself.

Manual cars are straightforward: check clutch bite point and flywheel noise.

Suspension, steering and brakes

The B8 platform's multi-link front end wears its upper control arm bushes as a matter of routine. You will hear a knock or clonk over speed bumps and poor surfaces, feel vagueness or wander on the motorway, and see uneven inner-edge tyre wear. It is usually done as a set of arms per side. Anti-roll bar drop links go the same way and rattle.

Steering changed at the facelift, which arrived at slightly different points depending on body style and market — so check the car rather than reading the advert's year. Pre-facelift cars use hydraulic power steering, so look for fluid leaks at the rack, pipes and pump, and listen for a whine on lock. Facelift cars use an electromechanical system with no fluid — faults there are electrical or in the rack assembly, and show up as a warning light or unexpectedly heavy steering. A steering warning or a change in steering effort is not something to drive on and think about later; get it diagnosed before you take the car any distance.

The electromechanical parking brake has actuator motors on the rear calipers that can fail, leaving a warning light or a brake that will not release. It also has to be put into service mode electronically before rear pads can be changed — do not let anyone force the pistons back.

S5 and RS5 cars fitted with the optional adaptive magnetic dampers can develop leaks; check for damp struts and any suspension warning message.

Water ingress, roofs and bodywork

Damp carpets and odd electrical faults tend to arrive together on this car, so treat one as a reason to look for the other.

The drains in the scuttle area under the windscreen block with leaves and grit, and water then finds the footwells and the wiring and modules that live low in the cabin. Lift the carpets — including under the seats — and press with your hand rather than trusting your eyes. Check the boot floor and spare wheel well too, and the seals around the rear light clusters. Cars with a sunroof have their own drain tubes that block in the same way.

On the Cabriolet, the roof drain channels are the classic fault: when they block, water backs up into the rear footwells and into the roof frame. Cycle the roof fully open and fully closed several times — it should go in one smooth movement without hesitating, and the hydraulic rams and pump should be dry with no oily residue in the roof well.

Bodywork is generally durable. On coupés and Cabriolets, check the frameless windows drop and reseal properly when you open a door, and listen for wind noise from tired seals.

Electrics, interior and the fault codes you will actually see

Common interior niggles include the seatbelt presenter arm on coupés and Cabriolets sticking or failing (the belt still works, but the arm is an annoying repair), MMI screens and control knobs playing up, and battery drain from a module that will not go to sleep. If a battery has been replaced, it should have been registered to the car electronically; otherwise charging behaviour suffers.

An airbag warning light on these cars very often traces to the wiring or connectors under the front seats, disturbed by seat movement. It still needs reading and fixing properly — never clear the light and hope, because with a fault stored the system may not deploy in a crash.

Codes that come up again and again on the 8T include crankshaft/camshaft correlation faults such as P0016 and P0017 (chain wear), camshaft adjustment codes like P0011 and P0021, P0171 system too lean and P0507 high idle on the TFSI petrols, P2015 intake manifold runner position on the diesels, P0299 turbo underboost, P0087 low fuel rail pressure and P2002 DPF efficiency below threshold. Damp cars often add lost-communication codes across several modules.

Because so many of these faults sit outside the engine control unit, a scan tool that reads every module and shows live measuring blocks is what actually settles them. VAGPULSE — the Windows software and cable sold on this site — does that across the whole car, including coding, adaptations and putting the electric parking brake into service position.

Test drive and pre-purchase inspection

Insist on a genuinely cold start. Most of what you need to know about the timing chain happens in the first two seconds, and a warmed-up car hides it.

Confirm the engine code and the gearbox on the car itself before you start, because almost everything above depends on which one you are looking at. Then work through this list, ideally with the seller present so you can ask about anything you find.

• Check the oil level and condition before the engine is started; ask directly about top-up frequency on a TFSI, and about a rising level on a diesel.
• Listen for a start-up rattle on any chain engine, and for a flywheel rattle at idle on a manual diesel.
• Drive a rough road slowly with the windows down, listening for front-end knocks over bumps.
• Test the gearbox properly for its type: crawling traffic and hill starts for S tronic, repeated pull-aways from rest for Multitronic, and kickdown for the tiptronic.
• On a Cabriolet, cycle the roof several times, fully, and check the rear footwells and roof well for damp.
• Lift the carpets, check under the seats, and look in the spare wheel well.
• Operate everything: parking brake on and off, all windows and their auto-drop, seatbelt presenter, headlights and daytime running lights, air conditioning at full cold, MMI.
• Ask for evidence of the chain tensioner update where relevant, timing belt and water pump on a 2.0 TDI, gearbox fluid services, and whether the diesel emissions service action applied to this car and was done.
• Scan every module for stored and pending codes, and check the emissions readiness monitors — an empty fault memory with monitors not yet set usually means something was cleared very recently.

Common questions