Aim for a B9 Audi A4 built from 2015, with proof the air-con heater element recall was done on 2015 to 2017 cars, and avoid the Multitronic automatic on front-wheel-drive A4s up to 2012.
19 known faults, 14 rated high severity in our database; owners report 41.8 mpg, 82% of the official figure. Everything below is built from that data and the archived owner history, not from a press car.
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Check an Audi A4 advert (free) →The B9 A4 (2015 to 2025) is the safer used buy, because the big engine and gearbox faults that wreck older A4s sit on cars built up to 2015: the 2.0 TDI PD oil pump drive, the piston rings on the 1.8 and 2.0 TFSI, the Multitronic automatic and the juddering manual clutch. That doesn't make a B9 trouble-free, so ask for proof that a 2015 to 2017 car has had the air-con heater element recall done.
Among B8s (2008 to 2015), a 2.0 TDI manual is the lesser risk, but only once you've felt for clutch judder pulling away in first, since recurring clutch and dual-mass flywheel failures are a known fault on it from as early as 20,000 miles. Be warier of the B8's 1.8 and 2.0 TFSI petrols: faulty piston rings make them burn a litre of oil every 500 to 1,000 miles between 50,000 and 90,000 miles, and it can end in engine failure.
The B5 (1995 to 2000) and B6/B7 (2001 to 2009) both suffer blocked drains below the windscreen: water backs up, gets into the electrics and can rust through the brake servo, leaving you with a rock-hard pedal. On the B6 and B7, don't touch a 2004 to 2008 2.0 TDI PD, whose oil pump drive shaft rounds off somewhere between 60,000 and 100,000 miles and destroys the engine.
The 2.0 TDI in the B8 and B9 is the diesel to shortlist, provided its cambelt has been changed at 60,000 miles or 60 months and, on a manual B8, the clutch doesn't judder. Its known weak spots are the EGR valve and DPF, which block up on 2008 to 2014 engines after the emissions software update, bringing a flashing glow plug light and limp mode.
Don't buy a 2004 to 2008 2.0 TDI PD (the BLB and BRE engines): its oil pump drive fails and takes the engine with it. The 2006 to 2009 2.0 TDI with Siemens piezo injectors was recalled for new injectors because a short circuit cuts the engine out, so ask for proof it's been done. The 3.0 TDI V6 loses coolant through its water pump and water-cooled EGR valve past 95,000 miles, and 2006 to 2008 cars get injector failures from 80,000 miles, signalled by white smoke.
Among the petrols, the 1.8T 20-valve sludges up its oil pump pickup between 70,000 and 110,000 miles, and the 2001 to 2005 3.0 V6 has a known fault with cracked blocks. The 2008 to 2015 1.8 and 2.0 TFSI burn oil past faulty piston rings, and 2.0 TFSIs up to 2017 were recalled because the extra coolant pump can clog and overheat. If it has to be a petrol, a B9 with proof of that recall is the lesser risk.
Avoid the Multitronic automatic on front-wheel-drive A4s from 2004 to 2012: its clutch pack and control unit fail between 60,000 and 100,000 miles, bringing judder from a standstill and then no drive at all. Audi called it a sealed unit, but its service schedule wants fresh fluid and a new filter every 40,000 miles, so a car without those receipts is a gamble. On a B8 manual 2.0 TDI or 1.8 TFSI, the clutch and dual-mass flywheel can need replacing more than once.
Press a hand into the carpet in both front footwells and feel for damp: blocked drains below the windscreen on 1995 to 2009 cars, and leaking bulkhead cable seals on 2008 to 2015 ones, let water reach the electrics. A brake pedal that feels hard and unassisted on a 2001 to 2009 A4 means trapped water has rusted through the servo. On a B6 or B7, especially an Avant, look at the inside edge of the rear arch lips, where rust starts before it bubbles through the paint.
Ask for it to be started from cold while you listen: a rattle on a 2008 to 2013 TFSI is the timing chain tensioner, and it only gets worse until the chain skips teeth. Accelerate hard and watch for blue smoke on a TFSI, then ask how often it's topped up, because the piston ring fault has them drinking a litre every 500 to 1,000 miles. White smoke from a 3.0 TDI V6 points to failing injectors.
On the test drive, pull away in first at low revs in a B8 manual 2.0 TDI or 1.8 TFSI: judder or slip means the clutch and dual-mass flywheel are on their way out, so ask for receipts and, on the 2.0 TDI, whether Audi's modified clutch release fork went in. In a Multitronic, feel for shaking as you move off and watch for a flashing gear display on the dash, and don't buy one that's reluctant to leave park or neutral.
Ask for proof of the air-con auxiliary heater recall on 2007 to 2017 cars, and treat a smell of burning plastic around the air-con as a warning. A 2.0 TFSI from those years needs the extra coolant pump recall, and a 2006 to 2009 2.0 TDI needs its injector recall. Get a cambelt receipt for a 2.0 TDI (60,000 miles or 60 months on the EA189 and EA288, 75,000 miles or 60 months on the earlier PD) and receipts for Multitronic fluid and filter changes every 40,000 miles.
Paste the advert into the free check and it runs these against the listing, the MOT history and the DVLA record before you travel.
A B5 is worth it only with dry carpets and brakes that feel right, because water's its big known fault: blocked drains under the windscreen, especially the one below the battery, let rain into the cabin, where it upsets the electrics, can damage the ECU and corrodes the brake servo. Make sure the immobiliser doesn't play up on any key. The body's galvanised, so look hard for accident repairs done with ungalvanised panels or poor welding.
Creaking from the front suspension means worn front wishbone bushes, and the front lower ball joints deserve a close look too. At the back, the rear discs are first to rust, and corroded unions where the flexible brake hoses meet the pipes at the rear wheels can dump brake fluid quickly, so get underneath and look. A4s from the 1999 model year were recalled to replace the track rod ends.
The TDI 90 and 110 were the popular diesels, and a loss of power above 3,000rpm on them is fixed by fitting a new thin hose between the turbo area and the ECU. Early 1.8 20v engines had plastic water pump impellers that fail, so ask whether it's had a pump with a metal one. The 2.6 V6's two catalytic converters rattle, and the 30-valve V6s can burn oil.
The 2.5 V6 TDI needs the most paperwork: it was recalled in 1999 for engine modifications, and its cambelt, which also drives the water pump, is due every 60,000 miles or 48 months, so ask for receipts showing both were changed together. Don't ignore the passenger door lock either: when it won't work, sound insulation inside the door caught in the mechanism is the usual cause.
The 2.0 TDI PD's oil pump drive is what kills these cars: on 2004 to 2008 BLB and BRE engines the drive shaft rounds off between 60,000 and 100,000 miles, oil pressure vanishes and the engine, often with the turbo, is wrecked. Watch for a red oil pressure light or metallic grinding from the bottom end. One owner was quoted £5,500 for a new engine and turbo on a 60,000-mile 2007 Cabriolet, and another paid £4,000 for a new oil pump before the engine failed anyway.
Blocked drains under the windscreen are a known fault here too, and on this generation the trapped water can rot through the brake servo, giving a hard pedal, and even get drawn into a petrol engine. There's rust along the rear arch lips on plenty of these, B6 Avants especially, so check for mismatched paint from a bodged earlier repair. A knock from the front suspension points to the anti-roll bar, which corrodes under its plastic collars until they split.
The 1.8T 20-valve petrol sludges up its oil pickup between 70,000 and 110,000 miles and starves itself of oil, while the 2001 to 2005 3.0 V6 petrol has a known fault with cracked blocks. The 3.0 TDI V6 goes through injectors from 80,000 miles on 2006 to 2008 cars, and one owner of a 2006 example was quoted £3,500, which Audi's contribution cut to £2,350. Don't take on a Multitronic without receipts for its fluid and filter changes.
It's a classy-looking car that feels classy inside too, and a Cabriolet adds a folding roof you should run through a full cycle, checking the fabric for tears and holes where it joins the body. Facelifted Cabriolets have had rattling windows. On a 2006 to 2009 2.0 TDI, ask for proof of the Siemens injector recall, because a short circuit in the original injectors cuts the engine out.
Real-world economy on this generation: Audi A4 41.6 mpg, Audi A4 42.4 mpg, Audi A4 Cabriolet 34.6 mpg, Audi A4 40.6 mpg, Audi A4 Avant 41.0 mpg, Audi A4 Allroad 36.6 mpg.
A B8's a sound buy only once you've ruled out its two big known faults: clutch and dual-mass flywheel judder on manual 2.0 TDIs and 1.8 TFSIs, and piston rings that leave the 1.8 and 2.0 TFSI burning oil. The clutch trouble can start at 20,000 miles and keep coming back: one 2.0 TDI manual Avant had its clutch and flywheel replaced at 20,000, 35,000 and 35,500 miles, and another owner's bill for a clutch and flywheel at 35,000 miles came to £1,500.
On the TFSI petrols, the piston ring fault shows up between 50,000 and 90,000 miles as blue smoke under acceleration, oil-fouled plugs and misfires, and it can end in engine failure. Audi counted a litre every 1,000 miles as acceptable, but owners have reported far worse: one 91,000-mile 2009 2.0 TFSI still needed oil every 300 miles after a new engine breather and a software update. Another owner paid £2,200 in labour for a rebuild, with Audi covering the parts.
Coolant leaks are the next thing to rule out. The 3.0 TDI V6 loses coolant from its water pump and EGR valve past 95,000 miles, and on 2013 to 2015 1.8 TFSIs a failed coolant regulator can send coolant up the wiring into the engine ECU, so the car won't start: one owner at 39,900 miles was quoted £4,085.58. EGR and DPF blockages on 2008 to 2014 2.0 TDIs after the emissions update bring limp mode and a flashing glow plug light.
Build quality's excellent, but water getting onto the front footwells through bulkhead cable seals is a known fault that can upset the ECU, and owners have reported front wheel bearing failures and a dead MMI screen, one owner being quoted £3,500 for a new control unit at 14,000 miles. B8 Multitronics up to 2012 share the gearbox fault, and one 58,000-mile 2012 2.0 TDI Multitronic needed a rebuild after its input shaft failed.
Real-world economy on this generation: Audi A4 40.6 mpg, Audi A4 Avant 41.0 mpg, Audi A4 Allroad 36.6 mpg, Audi A4 43.5 mpg, Audi A4 Avant 44.9 mpg.
The B9 has fewer serious known faults than older A4s, and two of them are recalls: 2015 to 2017 cars were covered by the air-con heater element recall and, on the 2.0 TFSI, the extra coolant pump recall, so ask for proof of both. The 272PS 3.0 TDI V6 on 2015 to 2018 cars has a known fault with vibration you feel in both the accelerator and the steering wheel at 1,250rpm and between 1,750 and 2,250rpm from 45,000 miles, along with a rough note when accelerating.
Owners of 2.0 TDIs have reported emissions parts giving up: one paid £1,500 to replace the EGR on a 2015 car at 60,000 miles, and another was quoted £930 for an AdBlue module control unit on a 2016 Avant. There's also a report of a 2016 manual shuddering in first as the clutch came up, which the dealer put down to a damaged dual-mass flywheel, so feel for that on any manual B9.
There's a good spread of economical engines, but owners have reported electronic faults too: a 2017 Avant that stopped dead from 38mph on an empty road because of a computer fault, a 2016 car whose pre-sense safety system kept triggering for no reason, and another 2016 car that needed a new engine management unit after breaking down twice. On an S4, one owner had two gearboxes fail within 25,000 miles.
Real-world economy on this generation: Audi A4 43.5 mpg, Audi A4 Avant 44.9 mpg, Audi A4 Allroad 44.9 mpg.
Sellers rarely admit these faults outright
Paste any Audi A4 advert and we check it against the faults, the MOT record and these figures in seconds.
Check an advert now (free) →Owners report 41.8 mpg across the Audi A4 engines with data, about 82% of the official figure, from 3,257 submissions.
Audi A4 Real MPG by engine →There's room for four large adults in a B9, with plenty of head and legroom, and the Avant's load area is sensibly shaped even if it isn't the biggest. The B9's cabin materials are first rate, it's quiet and refined on the move, and the Allroad rides broken road surfaces comfortably and quietly.
Quattro four-wheel drive keeps an A4 planted and stable in the wet, and the TFSI petrols are smooth and quick. The 3.0 V6 diesels are seriously rapid, the older 2.6 V6 petrol's a sweet engine, and the B5 handles tidily for a car whose engine sits out ahead of the front wheels.
Aim for a B9 Audi A4 built from 2015, with proof the air-con heater element recall was done on 2015 to 2017 cars, and avoid the Multitronic automatic on front-wheel-drive A4s up to 2012. Our database holds 19 known Audi A4 faults, 14 rated high severity, and the sections above say which generation and engine carry them.
The B9 A4 (2015 to 2025) is the safer used buy, because the big engine and gearbox faults that wreck older A4s sit on cars built up to 2015: the 2.0 TDI PD oil pump drive, the piston rings on the 1.8 and 2.0 TFSI, the Multitronic automatic and the juddering manual clutch. On the fault record the B5 (1995 to 2000) carries 1 known fault against 9 on the B6 / B7 (2001 to 2009). Each generation's section above gives the detail. Audi A4 faults by generation.
Press a hand into the carpet in both front footwells and feel for damp: blocked drains below the windscreen on 1995 to 2009 cars, and leaking bulkhead cable seals on 2008 to 2015 ones, let water reach the electrics. Read the MOT history for repeat advisories and ask for invoices for any work the seller mentions. Then paste the advert into the free check, which reads it against every known Audi A4 fault before you travel.
Owners report 41.8 mpg on average, about 82% of the official figure, from 3,257 submissions. Belt (2.0 TDI, EA189, EA288): 60,000 miles or 5 years, whichever comes first, so budget for it if the history does not show it done. The known faults page lists a rough repair cost against each fault. Audi A4 Real MPG by engine.
If you used the Honest John car-by-car reviews before the site closed in 2026, this is where the Audi A4 buying advice now lives. It is written from the archived owner reports and model notes (archived page, 282 items read for this model), our own known-faults database, the confirmed service intervals and the Real MPG figures. Every number on the page comes from that data, not from the text. The same data feeds our free advert check.
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The Audi A4 is one decision. Reading the advert, the history and the seller are the rest, and these cover them.
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