5 Post (s) Re: a6 3.0 tdi po401 insufficent flow – 27-09-2015, 11:03 AM. My insufficient flow message was from the nostrils blocked in the cast metal pipe leading to the inlet manifold, but as my EGR is operational I would get this. Cleaning process is highlighted here: Location. teeside. Jul 1, 2012. #2. I have a 2000 2.5tdi. I blanked mine of and it took around 10 mins. Just removed the engine cover off, removed the 2 bolts from the egr valve which loacte the pipe to valve, slipped in plate then reversed procedure. I. Access our free Vacuum Diagrams Repair Guide for Audi Cars 1999-05 through AutoZone Rewards. These diagrams include: Fig. Audi A4 2.8L Vacuum Diagram. Fig. Audi A4 2.7L Vacuum Diagram. Fig. Audi A4 1.8L Vacuum Diagram. Fig. VW Passat 1.9L Vacuum Diagram. Fig. VW Passat 2.8L Vacuum connections (top view) The purge valve on my c5 4.2 was near the firewall in the engine compartment on the passenger side. That is a pretty easy DIY job. The charcoal cannister is down by the gas tank kind of behind the right rear wheel. Probably need to remove right rear wheel and wheel well liner. I had my indy mechanic do this for me. Mass Air Flow Sensor. MERCEDES-BENZ. BMW. VW. FORD. PEUGEOT. NISSAN. Free and detailed step-by-step manuals with illustrations and video tutorials on how to replace AUDI EGR Valve will tell you how to carry out part replacement and car repair yourself. A quick video showing the contamination of urea within the low pressure EGR cooler on the CNHA engine fitted to various Audi models including A4,A5 and A6.Th On the back of the engine below the turbo, remove the heat shield from the EGR cooler valve and remove its plug. (Ignore the arrow below right for the exhaust gas temperature sensor, this pic is also used in another writeup). Remove the 2x 10mm 12 point bolts to free the low pressure EGR tube and set aside. The 2009+ Jetta, Golf diesel, and Audi A3 TDI have a more complicated EGR system. The low pressure EGR gasses are filtered before being sent through the cooler and back into the intake. The high pressure gasses go straight from the exhaust manifold to the EGR valve and into the intake. Here is a Playlist with all the videos I made about this car : 1. Disconnect the vacuum hose to the EGR and plug it. Connect a hose to the EGR, and while the car is idling, suck on the hose. The engine should stumble, if the valve and passages are ok. 2. If ok, the EGR temperature sensor may be bad (or the vacuum system plumbing). Reply Like. sUpTJI.