Modern fuel injected vehicles need a way to tell the computer how much air is coming into the engine in order to supply the appropriate amount of fuel. Most automakers do this with a MAF (mass air flow) sensor. The MAF sensor works together with other sensors in order to determine the amount of air that is passing by it. The ECU then interprets this data accordingly.
When this sensor is faulty it will result in numerous driveability issues. A quick way to diagnose it is to unplug the MAF and if your idle improves, then it needs to be replaced. Thankfully, this sensor is fairly easy to replace on a 1.8T.
You will only need a few tools, a wrench or ratchet to loosen the TIP clamp and a Phillips screwdriver. This article is based on the Audi A4 B6 chassis.
Parts
Audi VW Mass Air Flow Sensor - Bosch 0986280217
Audi VW Mass Air Flow Sensor - Bosch 0986280217
Procedure
First, remove the snorkel from the airbox. There are two phillips head screws in the front of the car holding the snorkel in place.
I have an aftermarket throttle inlet pipe which uses a different clamp than factory. I believe the factory one uses a spring clamp, so a pair of channel locks will help you open it up and slip it off the pipe. Mine uses a nut and bolt, so I just used a ratchet with a deep socket.
Move the TIP off to the side so you can access the two screws that secure the MAF to the airbox.
There's one on the top and the bottom.
Top:
Bottom:
Once you have the two screws out, the MAF should slide out. Now you can compare your two parts and check fitment. The installation of the new one is the reverse of removal.
About the Author: David Fresne
David Fresne is a Mechanical Engineering Student at SUNY Polytechnic. He likes to work on his B6 Audi A4 and motorcycle in his free time.
