O2 Sensors

[Big Bad Boris]

Hello all,

I have a 2005 2.0i Z4.

I have a recurring engine warning light issue. I purchased my own diagnostic tool which shows a code of P0420, which relates to either the cat. converter or issues relating to that not working efficiently.

However, the cat being the issue is too dire to contemplate, so my first thought is to check / replace to O2 sensors as they could be faulty. I did have one replaced around 3 months ago (in the engine bay on the drivers side). My initial question is how many sensors are there altogether, I know there will be at least one more in the exhaust somewhere.

Can someone please tell me exactly where the exhaust based one is located (and how difficult it would be to change myself) and how many there are altogether.

Many thanks,

BBB

[Elliot2000]

That particluar model car on that year with that engine used to suffer with exhaust manifolds cracking which caused engine lights and fault codes for o2 sensors and running lean. If it’s bad enough I could hear the blow when revved and sometimes u can see black staining on the manifold near the cracks

Btw the manifold and cat is all one piece

[E-bmw]

Did you use a proper O2 sensor or one of the generic ones?

You should stick with correct NTK or Bosch at a minimum.

[Big Bad Boris]

The sensor I used was a Bosch, so should be ok.

BBB

[Big Bad Boris]

Looks like looking for a crack is my next job....if it turns out that I need a replacement manifold and cat, where can I get one and how much is the damage going to be ££££?

BBB

[iSore]

Big Bad Boris said:

Looks like looking for a crack is my next job....if it turns out that I need a replacement manifold and cat, where can I get one and how much is the damage going to be ££££?

BBB

Get it welded - they can be reinforced as well. You don't want to know what the jokers at BMW ask for one.

• £1200 plus VAT.