Emissions light on after removal of middle box

[lucky7]

I had the middle exhaust box (the one under the doors) removed from my Z4 3.0Si and it has thrown up the emissions light on the dash. Has this happened to anyone else who has done this modification? Is there a way to have the emissions light put out or will I end up putting the middle box back on? I simply had two straight pipes put on in place of the box.

[Markos_Z4]

i have the same setup no resonator just straight pipes no problem so far !

most of the time emission light burns it give a camshaft sensor fail code ( thats what i have ) you get that code with a bad start !
it will go away in couple days ( reset )
if your z4 engine sputter you will have a defect Lambda Probe ( expensive parts ! you got 4 of them )
if your car has no power wen pulling up your MAF sensor is dirty ! clean it with air intake cleaner ! no brake cleaner ! ( very expensive part )

[Chris1981]

Same for me, no front silencer... or much of a rear silencer either but no engine light! Worth reading codes to find out what the error is... hopefully it's not a lambda sensor!

[Mr Tidy]

I hope it's not serious, and easily fixed OP.

A previous owner of mine had a custom cat-back system put on it - his next expense was lambda sensors!

[rally-chris]

One of my post cat lambda sensors failed following the removal of the original exhaust system to fit a cat back system, so I think they are prone to damage from work to the rest of the system (e.g. the inevitable grinding off of the rusty manifold studs and redrillling etc). You need to read the fault code to confirm, but beware my Indy tried two ‘cheap’ replacement O2 sensors and each time the light was back on within 10 miles! Fitted a new BMW part in the end (£££) and all was well.

Chris