Audi A6
EA839 turbo V6 with 250 kW and 48V mild hybrid. Successor to the supercharged V6, now with exhaust turbocharger. Very refined and powerful engine.
Mild hybrid makes the six-cylinder quicker
The DLZA in the A6 C8 combines a 340 hp turbo V6 with a 48V mild hybrid: the result is a drivetrain that feels surprisingly agile on pull-away thanks to electric boost, yet sips around 7 litres.
Engine Weaknesses 7
The EA839 DLZA (A6 C8, A7 4K, A8 D5) shares the known water pump weakness. Vacuum-controlled pump failure allows coolant to migrate into the vacuum system. Critical: 4-bolt pump still original, 6-bolt = already replaced.
Symptoms: Coolant warning light, coolant loss, P0299, 'drivetrain fault', start-stop disabled.
Early EA839 variants with poor-quality rocker arm rollers (GP0) are also possible in the DLZA. Rollers can fall out and cause camshaft and piston damage.
Symptoms: Combustion misfire, knocking from cylinder head, engine fault light, rough running.
The DLZA is fitted with a 48V MHEV. The belt starter-generator (BSG) and the 48V lithium-ion battery can fail. Control units before 2021 without moisture protection are vulnerable.
Symptoms: '48V system fault', rough starting, no recuperation, start-stop disabled, limp mode.
EA839 DLZA as a direct-injection engine without intake valve washing: oil mist from crankcase ventilation settles as coke on the valves. On long-distance A6/A7/A8 use often noticeable from 80,000 km.
Symptoms: Hesitation, cold-start weakness, power loss at part throttle.
Beyond water pump failure, EA839 engines in the business class (A6, A7, A8) also show coolant losses from seal failure. Regular coolant level checks important.
Symptoms: Coolant smell, dropping coolant level, overheating warning.
EA839 DLZA under high load shows elevated oil consumption from piston ring wear. With long service intervals in the A6/A7/A8 the problem can go unnoticed for some time.
Symptoms: Oil consumption above 0.5 L/1,000 km, bluish exhaust, oil smell.
In the extensively networked A6 C8 / A7 4K / A8 D5, occasional engine management sensor failures (boost pressure sensor, lambda) lead to the engine warning light without consequential damage.
Symptoms: Engine warning light, various fault codes, occasional power reduction.
Vehicle Weaknesses 6
Contamination of the bonding surface during manufacture can cause the rear panoramic roof module to detach. Affects A6 models produced in 2018.
On the A6 Avant (MY 2018), the rear glass panel of the panoramic roof was incorrectly bonded. Audi recalled 1,435 vehicles in Germany. Creaking/scraping noises and water ingress are further known issues with the panoramic roof.
Stress corrosion cracking can cause excessive play between the control arm and wheel carrier on the A6 C8 (MY 2019–2021), impairing driving stability. Recall by KBA (action 42L1), free repair at dealer.
High-voltage battery cell modules on A6, A7, Q5 PHEV models can overheat during charging (KBA 15722R / code 93AD). 53,449 vehicles worldwide, 17,012 in Germany affected (production period 08/2019–08/2024). Software update takes approx. 60 minutes.
The MMI infotainment system stands out for frozen displays, unexpected reboots and Apple CarPlay/Android Auto failures. Software updates only partially resolve the problem.
On some A6 C8s, water enters through a leaking wheel arch liner, causing musty smells and moisture in the footwell or boot.