Every full tank I have 2 occasions of rough idle and the radiator stays on

Tariq Khan

Registered User
Every full tank I have 2 occasions of rough idle and the radiator stays on

Hi, I have had my audi a6 c6 Le Mans 2.0 tdi le mans 2010 for over 2 years now. Car looks and runs beautiful but every full tank I have 2 occasions of rough idle (revs fluctuating up and down) and with that the radiator stays on for 20-30 mins after I stop the car. Also, car states on every full tank that I should get about 460 miles but I get between 320-350 miles per full 70 litres.

I had changed the pressure sensor last year as I went to get air conditioning refilled and it was not picking it up and the chap told me to change it. After changing the sensor, my air con got refilled which works now and my car was giving me 400 miles per tank after the pressure sensor change, so I don't know if this has anything to do with my car issues. Also, on a recent service, I noticed some green lubricant on the condensor when I was underneath the car.

Can you please recommend what I should do?
 

elan2s

Registered User
Radiator staying on would suggest a dpf regeneration cycle, which could also explain the idle speed changes
 

Tariq Khan

Registered User
Can this be required every full tank and what about the green colour liquid that I could see on the condenser. Is that condensation? Is my economy about right, when filling my tank up, is states I have 460miles on average, when I actually drive, each quarter is normally about 100 miles and the last quarter is only 30-50 miles meaning I do 330 miles to 350 miles. When I had my pressure sensor changed, I did 400+ miles for a few tanks but no it has gone back to the usual 330 odd miles.
 

abmat

Well-Known Member
VCDS Map User
We get about 420- 460, and that’s with very little motorway driving.
 

abmat

Well-Known Member
VCDS Map User
To be honest, no. It’s so subjective.

How well maintained it the car, when was the fuel filter last changed, serviced, gearbox oil, what tyres are fitted, driving styles etc.

All I would say is 350 is very low and it worth some further investigation as I’d be expecting at least 420.

I have vxcds so I can scan the car for fault codes, do coding etc.
 

Tariq Khan

Registered User
I agree, I don't know what to do? Mine is a audi a6 c6 Le Mans 2.0 tdi 2010, is mine a older model than yours? When I changed the pressure sensor, my economy went to 400-410 miles for a few tanks and then it started to go down and now it is back to about 300-350. The radiator stays on when there is rough idle, this can happen upto 2 times per full tank. On one of the posts, one guy said this is the dpf regeneration but should this be happening twice every full tank?
 

Tariq Khan

Registered User
To be honest, no. It’s so subjective.

How well maintained it the car, when was the fuel filter last changed, serviced, gearbox oil, what tyres are fitted, driving styles etc.

All I would say is 350 is very low and it worth some further investigation as I’d be expecting at least 420.

I have vxcds so I can scan the car for fault codes, do coding etc.
How much to check if there are any fault codes?
 

abmat

Well-Known Member
VCDS Map User
Most places charge circa £50.

or find a member near you and ask if they’ll do it for some beer tokens.

or just take it to a reputable garage and ask them to investigate the issue.
 
Top