Audi A6: 2.7 / 3.0 TDI EGR cooler soot clogging and coolant seepage
2.7 / 3.0 TDI EGR cooler soot clogging and coolant seepage is a common engine fault on the Audi A6 on the 2004–2011 cars, and we rate it major. Putting it right costs $1,500 to $3,500 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 34 documented faults on the Audi A6.
- Vehicle
- Audi A6
- Engine
- 2.7L / 3.0L
- Years
- 2004–2011
- Fuel
- diesel
- System
- Engine
What you are looking at
No photograph available
What goes wrong
The C6 A6 V6 diesels (2.7 and 3.0 TDI) have an EGR cooler sitting in the 'V' of the engine that clogs with soot and can crack internally, seeping coolant into the intake. It commonly throws a P0401 (insufficient EGR flow) and can cause rough running and reduced power. It is a labour-intensive location, and nearby plastic coolant fittings also crack with age. Very characteristic of these engines, especially urban-used cars.
What you would notice
- EGR / emissions fault code (e.g. P0401)
- Rough running and reduced power
- Coolant loss with no obvious external leak
- White smoke / sweet smell from exhaust
How to check it
Where to look. EGR cooler in the 'V' between the cylinder banks
Have it scanned for EGR flow codes. Check the coolant level and look for unexplained loss. On the drive, watch for a power flat spot and any warning lights. Ask whether the EGR cooler has ever been cleaned or replaced.
What it costs to put right
$1,500 to $3,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.
Ask the seller
- “Any EGR or emissions fault codes stored?”
- “Has the EGR cooler been cleaned or replaced?”
Now check the Audi A6 you are actually looking at
Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.
Where this comes from
- Audi Owners Club C6 EGR problem threads
- Go-Parts P0401 3.0 TDI guide
- Audizine EGR faults and coolant leak thread
Audi A6 buyer questions
Is 2.7 / 3.0 tdi egr cooler soot clogging and coolant seepage serious on a Audi A6?
We rate it major and common on the Audi A6. The C6 A6 V6 diesels (2.7 and 3.0 TDI) have an EGR cooler sitting in the 'V' of the engine that clogs with soot and can crack internally, seeping coolant into the intake. It commonly throws a P0401 (insufficient EGR flow) and can cause rough running and reduced power. It is a labour-intensive location, and nearby plastic coolant fittings also crack with age. Very characteristic of these engines, especially urban-used cars.
How much does it cost to fix on a Audi A6?
$1,500 to $3,500 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.
Which Audi A6 years are affected?
Our research records this fault on the 2004–2011 Audi A6. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.
How do I check for it before I buy?
Have it scanned for EGR flow codes. Check the coolant level and look for unexplained loss. On the drive, watch for a power flat spot and any warning lights. Ask whether the EGR cooler has ever been cleaned or replaced. Look here: EGR cooler in the 'V' between the cylinder banks