Hello everybody.

I have a 2011 A6 Allroad Avant 3.0L diesel with 173000 miles on it. I bought it a year ago privately and I am very happy with it. This is my 8th Audi, my 2nd Allroad Avant. 

Ever since I have had it, the EGR has been playing up with the MIL coming on. I get it switched off when serviced, but it comes back on after just a few journeys. I have had it diagnosed and it's showing a grade 3 fault with the EGR cooler/valve. (I was a VW/Audi mechanic some 50yrs ago, but these modern engines are beyond me!). I have used a few diesel cleaner additives, (Wynns, STP) which appeared to have worked, switching the light off, but only for a while. (My shortest journeys are usually 20 miles or more, I don't do short trips to the shops etc) 

From invoices provided by the previous owner I can see....

The EGR cooler assembly was replaced in Sep 2022 (Parts cost £655.94) at 139691 miles. (This is the wording from the invoice) 

A year later, Oct 2023 the EGR valve and cooler was replaced (Parts cost £707 inc VAT)  at 153795 miles.

I don't like having the light on as I am concerned that if another fault is detected with something else, having the light on already will not allow me to see this, and it could be a more serious fault.

Another Audi owner (A4 3.0L 2010 similar engine) says that I could have the EGR system blanked off, so that it is no longer operating, and so would not keep switching the MIL on.

He has had it done to his by a garage and it runs fine. The EGR and valve is still in situ, but it's no longer operating. He said that as there was less carbonised air feeding back into the combustion chamber, less was getting back into the sump, via the rings and so his oil was less contaminated. He showed me his dipstick (!) and I have to say it was the cleanest oil I have ever seen. It was amazing. 

It's my understanding that one of the main functions of the EGR is to reroute warm post combustion air back into the inlet manifold to get the engine up to operating temp more quickly. That seems like a good idea!

My questions are...

Is this a viable solution to the problem of the MIL lighting up?

Are there any consequences to having this work done?

Any help or information is greatly appreciated. 

Thank you

 

4 hours ago, Brian Howard said:

 It's my understanding that one of the main functions of the EGR is to reroute warm post combustion air back into the inlet manifold to get the engine up to operating temp more quickly.

The function of the EGR (exhaust gas return) valve is to pass some of the exhaust gas back into the engine in order to reduce emissions enough to meet modern criteria. Removing the EGR will thus increase emissions, though whether that increase will lead to an MOT failure I do not know.

Thanks Cliff. I understand, I wouldn't want to fall foul of that. I'll try and research that angle.

EGR gases also cool the combustion temperatures, reducing thermal stress on fuel injector tips, glow plugs and exhaust valves and everything downstream of the exhaust valves - Plus reducing NOx levels 

 

Thanks Mike. Worth keeping in mind.