Audi A5 40 TFSI B9

The EA888 Gen 3B uses an integrated water pump and thermostat housing made partly of plastic. The O-ring seal swells from oil exposure over time, and the plastic housing can crack under thermal cycling. Symptoms include low coolant warnings, puddles under the car, and erratic temperature readings. This is the most commonly reported failure on B9 2.0 TFSI engines across A4, A5, and Q5 forums. Many owners report the issue appearing between 60,000 and 100,000 km, though some early examples fail as early as 40,000 km. When one component fails, specialists recommend replacing both the water pump and thermostat housing together due to the integrated design. Independent shop repair costs approximately 800 to 1,100 euros (parts 350 to 500 euros, labor approximately 3.5 hours). Audi dealers typically quote 1,300 to 1,500 euros. Aluminium aftermarket housings from GRAF or similar are more durable than the original plastic. The widely quoted 8-year coverage for this component comes from a United States class-action settlement and is not a European Audi warranty, so check with your dealer what applies in your market before paying out of pocket.

All direct-injection TFSI engines are susceptible to carbon buildup because fuel is injected directly into the combustion chamber rather than over the valve surfaces. Carbon from crankcase vapours gradually accumulates on the intake valves, restricting airflow. Symptoms develop gradually: rough idle (especially when cold), hesitation during acceleration, minor misfires, and reduced power. These typically become noticeable between 80,000 and 120,000 km. Walnut shell blasting is the standard cleaning method. Independent specialists charge 600 to 800 euros, while Audi dealers charge 1,000 to 1,500 euros. This is not a defect but an inherent characteristic of direct-injection engines and should be treated as periodic maintenance. Short trips and gentle city driving accelerate the buildup. Using quality oil and occasional spirited driving helps slow the process but does not prevent it entirely. Audi does give this engine supplementary intake-manifold injection alongside the direct injectors, which washes the valves at part load and slows the buildup, but it does not prevent it.

Most A5 B9 40 TFSI models use the DL382 7-speed S-tronic, a wet-clutch dual-clutch gearbox. While significantly more reliable than the smaller DQ200 dry-clutch unit, it can still develop issues. Common symptoms include jerky 1st-to-2nd gear shifts at low speed, delayed engagement from standstill, and occasional gearbox malfunction warnings. The mechatronic unit (electronic valve body) can fail, with the driver position sensor (G676) being a documented weak point. Problems typically appear between 80,000 and 120,000 km, especially if the transmission fluid was never changed. Audi's own DL382 documentation specifies a gearbox oil change every 60,000 km, and specialists treat that interval as the minimum. Mechatronic repair at a specialist costs 1,200 to 2,000 euros. Full gearbox rebuild runs 2,500 to 3,500 euros. Manual gearbox cars (rare in the B9 A5) are not affected.

The PCV valve on the EA888 Gen 3B contains a rubber diaphragm that deteriorates over time, typically between 70,000 and 120,000 km. When it tears, symptoms include rough idle, a hissing or whistling noise from the engine bay, increased oil consumption, boost leaks causing power loss, and check engine light with lean or rich mixture codes. Diagnosis is straightforward: check for vacuum at the PCV breather port cap. The valve itself costs 50 to 80 euros for an OEM replacement. Labor requires removing intake components and takes approximately 2 to 3 hours. Total repair at an independent shop runs 250 to 350 euros, Audi dealers charge 400 to 500 euros. A failed PCV valve also accelerates carbon buildup on the intake valves, so it should be addressed promptly.