Audi A6 C8 40 TDI, 204 PS, 7-speed dual-clutch, all-wheel drive (2018–2023)

Research for this car

• Generation guide Audi A6 C8 (2018-2025): known problems and buying guide

  A quiet, roomy executive car with a costly 48 V generator risk on early cars, so check the generator and software history first.

• Engine guide VW 2.0 TDI (EA288) diesel: problems, costs and what to check

  Coolant leaks, EGR and AdBlue faults are the main risks. Buy with a cold-start check, a coolant pressure test and a full scan.

• Gearbox guide Audi DL382 7-speed S tronic (0CK): problems, costs and what to check

  A smooth gearbox when serviced, but mechatronic and clutch bills are large, so buy only with a scan and oil records.

Known issues for this car

Before you buy this car

From the generation guide

1. 48 V belt starter-generator: on a 2018-2020 car, start it from cold and look for a network warning. This check needs a scanner; a dealer with ODIS should read the generator and 48 V battery faults. Bad: a yellow or red network message, a warm idle stuck near 1,000 rpm, or start-stop switched off.
2. MMI and screens: test both screens, sat nav, radio, climate and driver-assist systems together. Ask for the software version and the date of the last update. Bad: a screen that freezes, lost favourites, or a warning that cruise control is not available.
3. Recalls: ask an Audi dealer to check open campaigns by VIN, especially the panoramic roof, passenger airbag and rear axle campaigns.

From the engine guide

1. Turbo (needs a scanner). Read boost faults and check the vanes. Bad: power loss, whistle or smoke.
2. DPF (needs a scanner). Read soot and ash loading. Bad: frequent regeneration or high oil level.
3. Intake manifold (pressure test). Pressure-test the cooling system. Bad: coolant loss with no puddle, worse under load.
4. EGR cooler (pressure test). Cap the cooler hoses and repeat the test. Bad: it holds only with the cooler bypassed.
5. AdBlue and NOx (needs a scanner). Read NOx sensor and dosing faults. Bad: an emissions warning, a restart countdown or crystallised AdBlue.
6. Water pump and heater. Start cold; heater must blow hot. Bad: weak heat, wandering gauge, dried coolant.
7. Oil pump drive (needs a scanner). Listen for a rattle at idle and check for oil-pressure codes. Bad: a red oil-pressure warning.
8. Belt and pump invoices. Ask for dated belt, pump and thermostat invoices. No record means budget for a belt job.
9. Recall check. Enter the VIN in the official recall check. Bad: an open 23Z7 campaign on a T6.

From the gearbox guide

1. Mechatronic scan (needs a scanner). Read the gearbox fault memory for P0718, P0811, P0607, P179B and P17D1. Bad result: stored faults or a recent limp mode.
2. Cold clutch test. Pull away uphill and reverse up a ramp, twice. Judder means clutch work.
3. Pump motor history (needs a scanner). Check for pump and circuit board faults. A failed motor can stop the car.
4. Speed sensor campaign. Ask a dealer for campaigns 34 22 54 and 34 23 62. Scan for P0718 and P2768.
5. Gear position sensor (needs a scanner). On cars up to 2018, check the key comes out in P and the display lights.
6. Oil leaks. Check the plastic pan, mechatronic and housing joint.
7. Oil records. Look for 60,000 km oil changes with G 055 529 A2. Stamps prove nothing.

Running costs

ADAC figures for 15,000 km a year over 60 months

ADAC versions