Audi A6 C5: How to Replace Fuel Injectors

This guide will show you how to replace the fuel injectors in your Audi A6 C5, which are critical parts to your engine performance.

By Bassem Girgis - April 6, 2016
Contributors: RLG

This article applies to the Audi A6 C5 (1998-2004).

The fuel injectors are little devices that inject the proper amount of fuel into your Audi A6 C5's engine. When one or more of these parts go bad, it affects the air/fuel ratio, thus affecting the performance of your vehicle. You Audi will start hesitating, you may experience sluggish acceleration, and it if gets too bad, your car can fail to start. Even though replacing the injectors isn't a hard process, in the Audi A6, you will have to remove literally tons of parts. Be sure to take pictures throughout your process to remind yourself of the location of all the small parts. If you feel like you're up for a little challenge that will save you a lot of money, read on to learn how to replace the fuel injectors in your Audi A6.

Audi A6 C5: How to Replace Fuel Injectors

Materials Needed

Socket set
Phillips screwdriver
Pliers
Allen wrench
Wrench
Flat head screwdriver

Step 1 – Remove Y-pipe

Remove the giant Y-pipe on top of the intake manifold. It is held in place by three 10mm bolts. However, you will need to disconnect it from the intake tube, which can happen by squeezing the clamp with your pliers, then pulling the intake tube away from it. Then disconnect the two other hoses on the other side of the Y-pipe, which are the upper inlet hoses, you can do so by also loosening the screw on the worm clamp, then disconnecting them. Remove the three bolts holding the Y-pipe in place. Use a flat head screwdriver to remove the hose circled in blue. Just push on its plastic tab, then pull it away.

AUDI A6 C5 C6 FUEL INJECTOR REPLACE REMOVE CHANGE HOW TO — Figure 1. Remove Y-pipe.

Step 2 – Remove all connections to fuel rail

To access the fuel rail, we have to remove all the parts connected to it. Looking at Figure 2, remove the electrical connection on the top left, then remove the electrical harness from the N80 valve, which is right next to the other connection. Remove all the hoses circled in green (you will have to use your flat head screwdriver to loosen the worm screw), then slide it away from the connection, and then disconnect the hoses. Expect some fuel to leak as you remove some of the hoses. Most of the hoses will have a worm clamp, but the supply line will have a nut, so you will need your wrench to remove that.

Step 3 – Disconnect injectors' harnesses

Disconnected all of the fuel injectors' harnesses. You will have three on each side; you just need to depress the metal clip on each, then pull them out to disconnect.

Step 4 – Remove fuel rail

The fuel rail is held in place by four Allen bolts. Remove all four of the bolts, then pull the fuel rail up and out.

Step 5 – Replace injectors

Remove each injector from the fuel rail. They are held in place by a metal clip; you just have to pop it off, then pull the injector off. Install the new injectors in place, then install the metal clips back on.