Audi A4 B7 2006 DPF replacement guide Read the whole guide first to make sure you are
 

The time has come when you keep getting that flashing heater plug light symbol on your dashboard. You’ve tried the additives, you’ve changed the oils and filters. The car has been in limp mode, you have to stop switch off, start again and hope and pray that you get home. But, now you’ve decided to buy a new DPF (pattern part with a 100,000km guarantee) and fit it. Here’s how I did it. I hope it helps some poor soul.
1. Find firm and level ground to work on.
2. Put on car ramps to allow access to front underside of vehicle
3. In gear/park, handbrake on, chock the rear wheels for safety
4. Open bonnet disconnect the negative side of the battery
5. Remove the plastic engine cover by removing the three 10mm nuts.
6. Remove the entire air filter housing completely by disconnecting hoses and the electrical connector on the top of the air filter housing
7. Remove the plastic under trays from under the engine and gearbox by unscrewing the special securing screws. Stow away the items for future rebuilding in a safe place, keeping all removed fasteners in a suitable container.
8. The DPF will now be half visible down the side of the engine under where the air filter housing was secured. At the front end of the DPF you will find two sensors attached with a nut style fitting. These two sensors are best removed at this stage using suitable sized spanners, please make sure that you firstly follow the attached wire from the largest sensor (I think it’s a lambda-sond) to where it begins and disconnect the plug at the car bulkhead/ firewall (only the larger of the sensors is like this the other smaller one if I remember correctly can simply be undone without twisting therefore not damaging the wiring). The larger sensor can now be unscrewed after gently guiding the wires so that the wires remain straight and untwisted during unscrewing. Please note that the Lambda wire is secured to the engine side in two places, one is a simple two toothed holding device, the other is a plastic tie wrap type thing, I had to cut the tie wrap thing with wire cutters in order to release the wire. After rebuilding you must re-secure the wire using a new plastic tie.
9. Further toward the rear of the DPF you will find to small bore steel tubes connected to rubber hoses. I did not attempt to remove the nuts holding the tubes to the DPF (very very tight), instead I undid the small hose clips holding the rubber hoses to the steel tubes (ensure that you label the tubes to ensure correct refitting when reassembling.
10. At this stage remove the three nuts holding the DPF to the rear of the turbocharger.
11. Under the car now remove the two exhaust mounting clamps which are under the rear of the DPF. This job is a pain in the neck with very little working space. Take your time and remove the clamps.
12. The DPF now needs to be removed from the rear (exhaust pipe connection). Again this needs patience and a couple of very long 1/2 inch drive extensions to remove the nuts. On my car, all threes studs snapped when I tried to remove them (rust and corrosion)! This does not affect the job because there are new studs on the new DPF. TBH I was glad to be even able to reach them! Because the DPF had been removed from the turbo charger it does allow a small amount of room to get access to the nuts on the studs.
13. The DPF is now ready to be removed through the ridiculously small gap at the side of the engine, in order to make this job slightly easier, I removed the silver coloured pipe on the engine which is attached with two Allen head bolts on the left and two nuts on the right. (Make sure you don’t lose the two thin metal gaskets that are used at either end of the pipe). You must now gently remove the DPF through the small gap, it was like birthing an oversized steel baby (at times I had to gently push the engine to the side and lift and pull and guide the attached small bore steel tubes around all the various items getting in the way). With love and serious patience you will be rewarded with the old DPF being out of the engine bay. Again, time patience and not losing your temper are all vital attributes in order to not break any surrounding components.
14. At this stage take a break, the worst of the work is behind you.
15. Now we are going to replace the DPF.
16. At this stage, you must remove the small bore steel pipes from the old DPF. I was astounded at how tight they had been bolted on. Once the tubes are removed, I carefully using pipe-cleaners (available from all good tobacconists) cleaned out all the soot from the inside of the pipes. After all was clean, I attached the pipes onto the new DPF making sure that I got them the right way round. The new DPF I was supplied with, had two additional metal side securing clips to keep the small bore pipes tight against the side of the DPF. They were designed in such a way that if you were to tighten them up as would be required, you would put excess stress on the small bore steel tubes. For that reason, I only lightly tightened them to ensure they don’t over stress the small bore tubes.
17. Luckily the new DPF is a good deal smaller than the original which helps dramatically when putting the DPF into the small access area. Once I had the DPF in the approximate position, I carried out the following:
a. Attach DPF to exhaust pipe (ensuring the front of the DPF in in the approximate area to connect to the turbo (new gasket are required for both ends of the DPF).
b. Attach front of DPF to the turbo.
c. Attach the exhaust support clamps back into position.
d. Reconnect the small bore tubes to the rubber tubes using the hose clips.
e. Re-attach the two sensors. Reconnect the lambda-sond to the connector at the bulkhead.
f. Replace the air filter housing and electrical connector.
g. Now go around the engine bay making sure that anything you have temporarily removed for access is now replaced. Make sure that all wiring is secured tidily away from parts that are going to get very hot (turbo/DPF). Make sure you have recovered all the tools you have been using.
h. Now reconnect the battery.
Now all this work is over, it is IMPERATIVE that the cars ECU is reset to zero for the DPF system Using the correct software. My local mechanic also ran a couple of other software resets that he said would be good to do. Make sure you get a receipt from the mechanic showing that you have had the reset work done (this is to protect your warranty on the new DPF).
i. Take the car for a test drive and make sure that the exhaust is not blowing etc. After this stage you can now replace the under trays for the engine and gearbox and the under bonnet engine cover.
Please understand that this is only a guide, I’m not saying that it will be a guarantee that the DPF will work. I’m not implying that this is the textbook way of doing the job. It worked for me, I hope it provides some idea as to what is required. On a scale of 1-10 in difficulty, this job is easily a 7.