The fuel filter on the A4 is a funny thing. No, it’s not really any different than other fuel filters you may have encountered, nor is it really that difficult to get to. Rather, to quote from the Bentley manual, “Audi specifies that the fuel filter used on all engines is designed to last for the life of the vehicle. There is no routine replacement required.”
This is a bit surprising, but automakers are extending service intervals all the time for things like transmission fluid, coolant, and even engine oil. When you consider, however, that Audi has no control over the quality or cleanliness of the fuel at your local filling station, and the fact that a few turbo owners out there may be turning up the boost (thus needing a more robust and unrestricted fuel supply), the ability to change the fuel filter is necessary.
If you’ve got a 1.8T quattro, you’ll find that Audi’s disinterested attitude toward your ability to change your fuel filter is reflected in the facility they provide for its replacement. The biggest hurdle is clamp that holds the filter in place underneath the car, wedged between the fuel tank and the body. That clamp is held tight by a bolt that is tantalizingly visible but inaccessible using a socket or even a standard L-shaped wrench.
The solution? Lower the fuel tank a bit (the plastic clamp for the fuel pump is attached to the tank itself) and suddenly the bolt becomes accessible. After that, the rest is like any other fuel filter replacement; remove the two hoses that feed in and out of the filter, attach those hoses to the new filter with new metal washers/gaskets, and put the filter back into place.
Here’s the fuel filter in situ. The camera is pointing up, with the front of the car to the right. The black plastic fuel tank is on the left. The banjo connection at bottom of the fuel filter is the feed line from the fuel tank, and the line snaking out and away from the filter, near the rusty-looking bolt seen just below the filter, feeds fuel to the engine. That rusty bolt is the clamp bolt that holds the black plastic collar tight around the filter. The large hose on the right is the fuel return line (from the engine back to the fuel tank), and the black line to the left is the parking brake cable leading to the passenger side rear corner.
Unfortunately, the gap you can see between the head of the bolt and the body of the car is not large enough to accommodate even an L-shaped Allen wrench, let alone a socket and ratchet.
To gain access to the clamp bolt, the best solution is to lower the fuel tank a bit. The fuel filter clamp is part of the corner of the fuel tank, so by lowering the tank you move the clamp bolt away from the body of the car and increase the clearance.
The tank is supported by two straps, and the ends of each strap are connected to the chassis by 13 mm bolts. Remove these four bolts and you can lever the tank down enough to gain the necessary clearance.
Before you start removing lines from the fuel filter, loosen the fuel filler cap to release any built-up pressure in the system. You’ll still leak fuel when you remove the fuel lines, but it will only drip out, not spray. The lower banjo bolt for the fuel feed line has a 19mm head on it. It’s easiest to remove the bolt now, while the fuel filter is still held tightly in place. Make sure to have rags and a catch pan ready to catch and mop up the fuel as it flows out.
As you can see, with the fuel tank lowered slightly, I now have room enough to fit an L-shaped, 6mm Allen wrench onto the clamp bolt. The bolt is actually a triple-square fastener, but an Allen-head wrench will work on it.
As you lower the fuel filter away from its mount, note the line still attached to the top with its own banjo bolt. In the background is a hammer
- I used the handle as a lever, wedged between the fuel tank and the body of the car, to force the front of the fuel tank to tilt down enough to gain clearance for the clamp bolt.
The top banjo fastener can be loosened with an 18mm wrench or socket. I found that I could counter-hold the filter with a 22mm wrench on the hex-shaped boss surrounding the attachment for the lower banjo bolt.
The top banjo bolt is on the left, and the bottom one is on the right. Note the larger holes in the bolt that feeds fuel from the fuel pump into the filter. This bolt also has a larger head, 19mm versus 18mm.
Each banjo connection has two metal washers that must be replaced. Two 12 x 16 x 1.5mm washers surround the end of the line leading away from the fuel filter, and two 14 x 18 x 1.5mm washers surround the end of the fuel filter feed line, just as
the picture shows.
Rather than simply reinstall the corroded clamp bolt, I applied a little
shadetree engineering and used a zip tie to secure the fuel filter back into place. It’s not as secure as the original clamp, so I’ll check it again soon and make sure it’s staying in place. If it works, it will make subsequent fuel filter changes much easier and won’t require the lowering of the fuel tank.
dont know if you can help
i changed a fuel filter and now car wont start
it started after changing but then shut down
audi a3 2007
August 16, 2014
Followup from the Pelican Staff: is the filter installed correctly? In the right direction? I can't help without knowing what is missing from the system when you are trying to start it. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
Comments: I just did my b5 1.8t. Blow in the old one to see the restriction. Mine was horrible.
July 24, 2014
Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
Comments: Great article.
I need to change out a fuel pump for a friend and certainly do not want to take a chance that the pump loaded the lines up with trash as it was dying.
I always thought that a fuel fiter change was annual maintenance, so this was surprising to hear from a high end car company. They are not the only company that has little regard for techs at the service end.
Thanks for taking the time to put the article together.
August 25, 2013
Followup from the Pelican Staff: Thanks for the feedback. Glad we could help. - Nick at Pelican Parts
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