Emission fault light in 2007 Z4

[jeremygray]

I mentioned to the forum a few weeks ago about my emission fault light, and despite my indys checking, could find no fault and reset the computer. After this had happened a but 4 times I took it to BMW for a full diagnostic test who advised me to replace the wiring loom, cat and sensors at a cost of £3,600....
I went to a German car specialist who I have not used before and they suggested bringing it back when the fault code reappeared as they could not properly check as the computer had been reset by BMW.
In the meantime a forum member said he had had a similar problem and put a shot of Redex in the tank and took it for long run. Not holding out a lot of hope but nothing ventured etc bought a bottle of Redex put half in a full tank of petrol as per the instructions and then started on a preplanned visit to Scotland a return trip of about 600 miles.
Predictably the emission light came on after 20 miles and I continued on my journey as the car was running well. Much to my surprise the light went off after 200 miles of mostly motorway driving and has so far remained off- I have put the remainder of the Redex in a full tank of petrol.

Anyone have any thoughts-was it the Redex or the good long run-anyway I am most grateful to the member who made this suggestion.
What would you do now?
Thank you.

 

[Derby Z4]

I had the same problems as you.Emission light coming on but the car still running sweet.
I would say that you need to drive it harder,since I have been doing that the light hasn't come back on.
Get yourself one of these to reset the light when it comes back on.
http://www.ebay.co.uk/itm/110937239971?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
I would say that it was the good long run that sorted it,
Don't be afraid to give it some revs,the zed will thank you for it !

 

[jeremygray]

Thats helpful advice thank you.
I will buy a scanner reader to reset the warning light if it comes on again.
I have never used one before where do you plug it in on the Z4?

I much appreciate your help thanks

 

[Gargybloke]

Lets hope it was just that, it can be.

A dealer had my Citroen for a service and a gearbox recalibrate. Looks like they over filled my oil change then took it for a run to check the gearbox. I always check the oil after a garage has done anything before driving off so noticed it. Got them to re-do it because they couldn't work out if they had put new oil on top of old it was so dirty.

Anyway after oil was correct I started immediately getting a fault code for the EGR valve. They wanted £600 quid to change it, car worth £2200. They wouldn't admit that the overfill and driving might have caused it. Told them to sod off and drove the car harder through 4 tanks of premium diesel and some diesel redex. Really running sweet now and no engine light

What petrol do you put in?

 

[andysat]

Thats helpful advice thank you.
I will buy a scanner reader to reset the warning light if it comes on again.
I have never used one before where do you plug it in on the Z4?

I much appreciate your help thanks

Under the dashboard.

 

[Lillywhite]

Under the dashboard.

Yes you will see a small plastic hinged cover to the ridgt of the dashboard near the drivers door hinges where you plug in the 16 pin plug. Switch the ignition on, select 'BMW' and away you go. Very easy to use. :wink:

 

[jeremygray]

Many thanks for all the helpful comments.

I use ordinary unleaded but may switch to premium and try a couple of tankfuls.
Thank you.