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 gas leaking at the fuel injectors. Replacing the fuel injector O-rings typically would be done when the fuel injectors would already be removed.
For example, when you need to remove your intake manifold, the fuel rail and fuel injectors need to come out. It’s good to perform this preventative maintenance and replace the O-rings at this point. They’re cheap, and it’s great insurance to not have to deal with an issue in the future.
Parts & Tools Needed
You’ll need a set of (4 qty) 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 states that it is for a Ford F-150, 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.
To remove the fuel injector O-rings, use a straight pick tool to get behind the O-ring and lift it out. The O-rings are a very tight fit, so this is probably the best way to get the O-ring off of the fuel injector. Do this for the (4 qty) O-rings.
Prior to install new O-rings on each of the fuel injectors, lubricate them with clean motor oil. Then press them over 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. Yes, I have made this mistake before on my old E46 M3 and it was a such a pain to have gasoline leak all over the floor, and having to redo the job just to replace the O-rings again.
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 fully in. 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.
