Audi A4 B8 130,000 miles No fault codes Has an after market DPF fitted White smoke and diesel fumes for approx 40 miles then stops - nothing! Never any loss of power. Thirsty on diesel when smoking. Can go through many tanks of diesel before it happens again. Switch off leave overnight and it will continue the problem until it's 40 miles is up. The car has been at Audi for over 3 weeks now, they replaced the ERG valve and ensured that I was spending 900 pounds wisely. Did not fix the fault. Any one got any ideas?