The need to change out your fuel injector O-rings on the MK1 Audi TT usually isn’t something that is needed unless you have an issue like a gas leak at the fuel injectors. Replacing the fuel injector O-rings would typically be done when the fuel injectors need to be removed.
For example, when you need to remove your intake manifold, the fuel rail and fuel injectors need to come out. It’s a good idea to perform this preventative maintenance and replace the O-rings at this point. The fuel injector O-rings are cheap, and it’s great insurance to do them now and not have to worry about it in the future.
Parts & Tools Needed
You’ll need a set of (4 qty) fuel injector O-rings, which you can find on Amazon. The FEL-PRO kit (part number: ES 70599) is a popular set, which is a direct fit for the MK1 Audi TT. The Amazon listing I’ve linked to below states that it is for a Ford F-150 in its title, but it is actually a direct fit for the 2000-2006 Audi TT (same O-ring size). A critical tool to have for removing the old O-rings is a straight pick tool.
Fuel Injector O-ring Set: FEL-PRO ES 70599 Fuel Injector O-Ring Kit
Straight Pick Tool: Uxcell Straight Pick Tool (2pc)
Changing Out the Fuel Injector O-Rings
I won’t go through the process of removing the required parts to get to this point since you wouldn’t typically go through the hassle just to replace the fuel injector O-rings. As I’ve mentioned at the beginning of this post, these O-rings are usually replaced because the fuel injectors and rail are already removed.
When I replaced my intake manifold gasket, I had to remove the fuel rail and injectors. Upon close inspection, I noticed that the O-rings for the fuel injectors were hardened, so I figured it was only a matter of time until it would lead to a fuel leak. This is now an opportune time to replace these O-rings.
To get the fuel injector O-ring off of the fuel injector, use a straight pick tool to get underneath the O-ring and lift it out. The O-rings are a very tight fit, so this is the best way to get the O-ring off of the fuel injector. Do this for the (4 qty) O-rings.
Prior to installing new O-rings on each of the fuel injectors, lubricate them with clean motor oil. Then press them onto each fuel injector with your hands. I don’t recommend using the pick tool for the installation as it is possible you might puncture the new O-ring and cause a gas leak. I made this mistake before on my old E46 M3 and accidentally punctured the O-ring, causing gasoline to leak all over when everything was reinstalled. So, just use your hands to roll the new O-rings onto the fuel injectors.
Once the lubricated O-rings are back on the fuel injectors, reinstall the fuel rail and injectors very carefully. Again, you don’t want to damage any of the O-rings (even a slight nick could cause fuel to leak.)
Ensure that the fuel rail goes in completely, with all four fuel injectors seated in fully. The fuel rail would then need to have each injector’s connector plugged back in, and any associated clips reinstalled to the rail. That completes the job of replacing the fuel injector O-rings, which guarantees you don’t have to worry about those O-rings for a long time to come.
