Lambda sensors for N52 3.0si

[ryushe]

Let me preface by saying I've found a ton of threads about lambda sensors, but can't find a clear answer to my question (or I'm just too dense to understand the answers -- take your pick ).
I've been getting very intermittent yellow check engine lights on my 3.0si for a while now (like once every 2 months), which go away for quite some time after clearing codes. The fault codes I get have to do with the pre and post cat lambda sensors.
So I've decided to finally replace them, given the noted faults, the mileage on the car (around 110k miles), and my suspicion they've never been replaced before. I've figured out I need two sensors before the cat, and 2 sensors after the cat, and have so far decided on Bosch sensors.
Question is, before I order them, can anyone confirm the below sensors are the ones I actually need to replace the whole set?

Pre cat
BOSCH 0 258 017 100
BOSCH 0 258 017 098

Post cat
BOSCH 0 258 006 755
BOSCH 0 258 986 602

Thanks!

[.adam.]

I've just ordered the post cat sensors you have listed, getting them changed (assuming they are faulty), on the 4th June, so I should be able to tell you if they are correct! I got mine from Autodoc, and paid the small extra charge for the free returns just in case they are wrong.
The only thing that confused me is Autodoc list 4 different post cat Bosch sensors, but one pair is twice the price, so I ordered the cheaper ones in the hopes that they will be okay.

[ryushe]

The only thing that confused me is Autodoc list 4 different post cat Bosch sensors, but one pair is twice the price, so I ordered the cheaper ones in the hopes that they will be okay.

Yeah, that was part of my confusion as well, hence the question
I was planning on fitting them myself though, doesn't seem that complicated?

[jamiecarpenter]

I have the same issue intermittent light coming on. Garages seem to be reluctant to change it possibly due to the exhaust being so old. Is it a case of taking the exhaust off?

[Joycey]

Most garages see the crusty looking exhaust flanges and don't want to touch it. Best get those old bolts removed then install new sensors, quite often its these old bolt allowing air into the system and throwing an error on the Lambda.

[j3nks79]

You need to investigate for air leaks before throwing money on lambda sensors.

[.adam.]

Just to update, had the sensors fitted today, which solved my eml problem. The sensors did fit, although one was a universal fit, which meant it had to be hard wired, which caused some extra time diagnosing as it wasn't plug and play like the other one listed above.

[Thermaltake]

the 4 different listing on autodoc are usually 2 are the universal, the 2 more expensive ones are usually the connecter's pre-fitted. you can cross reference with bosch's website which will tell you specifically what code is which.