How to replace the AUC Sensor -E89 30iSDrive-

[Varixto]

Recently, I have had an AUC error code, which indicated that the AUC sensor was faulty.
Firstly, I bought the sensor at my local BMW dealer (not cheap...).
Then, I tried to figure out how to get to it. Some people where saying that you needed to get the whole scuttle panel out but other people said that you could get away by undoing a few clips on the passenger's side. Please note that I'm based in the UK so my car is RHD.
So...here's what I did:
1) I unclipped all the clips in the positions (roughly) indicated by the arrows
Note: these are really brittle....be careful


2) I then could gain access to the area where the AUC sensor is:
3) I unplugged the negative battery terminal and unplugged the sensor.
4) You must twist clockwise the old sensor about a quarter turn to be able to remove it. The new one is completely different. It's facing the engine, while the old part was perpendicular to it, facing the passenger's side wing.
5) Once done, refit in reverse order and clear the error code (I don't know if this is necesssary but I did it anyway).
Hope this helps people with the same issue.

 

[B21]

Good write up…

Mine’s goosed ..again..

Not sure if I’ll use your technique or go the full BMW route ..

 

[flybobbie]

Whilst scuttle off place some mesh across the air intake, otherwise the cabin filter box fills with leaves.

How do i know

 

[B21]

Whilst scuttle off place some mesh across the air intake, otherwise the cabin filter box fills with leaves.

How do i know

Yup good move

 

[fraserj]

Good instructions, took about 10 minutes. Easier with those fixings if you have a trim removal tool.

 

[paul1969]

Hi all,

Carly has flagged up a fault on my Z4 for the AUC sensor. I’ve seen the posts above on how to replace it, but I’m just wondering — is this strictly a BMW-only part, or are there any decent aftermarket options available?

 

[B21]

Hi all,

Carly has flagged up a fault on my Z4 for the AUC sensor. I’ve seen the posts above on how to replace it, but I’m just wondering — is this strictly a BMW-only part, or are there any decent aftermarket options available?

Only bmw specfic part…must fit mine this winter. ..you could try Autodoc to see if they offer a oe compatible part

 

[Reamesy]

Don’t bother with used parts either. They are prone to failure so with no history and no way determine if it’s faulty until it’s fitted. Just buy new and have done.

 

[Varixto]

Don’t bother with used parts either. They are prone to failure so with no history and no way determine if it’s faulty until it’s fitted. Just buy new and have done.

I agree. I bought a brand new OEM part and so far it has not given me any trouble (touch wood).

 

[Varixto]

Only bmw specfic part…must fit mine this winter. ..you could try Autodoc to see if they offer a oe compatible part

I don't know if it will really make a difference but perhaps it might be better to change it now if you can (ie: in the late summer), as I think that the plastic bits won't be as brittle as in a cold winter day. However, new plastic fittings/clips from BMW are cheap. So if you do it yourself in the winter, it might be a good idea to buy a few of those, just in case you break some in the process.