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I bought Audi A5 3.0 TDI 5 years ago (2010 MY11, coupe) with 42kms on the clock. Two years later, check engine light came up. Took it to the mechanic and he id the fault as “P0402 – EGR insufficient air flow - intermittent”. He did some cleaning and said probably EGR valve but it could be many other things – he told me it could cost thousands of dollars to establish what is the problem. The following 3 years I have been driving the car with this light coming (and going) on a regular basis – more frequently during summer months than during winter. There is no loss of power, the car runs really well; maybe a bit rough in neutral, not sure I can actually gauge. From time to time it ends up revving up in neutral (800 revs vs normal 620) and smells “hot” when I switch it off. “Rev up” sometimes disappears even during the drive – I can feel it when I stop at lights…

I tried using Liqui Molly Diesel Engine intake decarb – no change… I also tried Revive for turbo diesel engine and there was very little (if any) white smoke showing “de-carbonisation” and, from what I saw, the turbo was spotless…

After 5 years of this (105kms) I was tempted to go for EGR delete. However, I decided to change EGR valve instead. My cousin did it for me, so I know it was a thorough job. He only changed the valve – he cleaned the cooler and said it was flowing well. He also cleaned and tested “the flap” (?? not sure what he meant by that). Also, he did manual DPF burn as it was showing 46% …
In any case, you can guess it – the dreaded “check engine” light came up again and it is the same fault code.
Can anybody offer any comment / advice???
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