C350 M276 Petrol Engine - Nox sensors

[ash1212002]

Looking to purchase a c350 petrol which has the m276 engine.

From what I've researched it appears there are many problems with the nox sensors where they have been replaced but the problem still persists or the issue rears it's head again; users reporting they've replaced the nox sensors a number of times.

Has anyone managed to figure out the root cause as to why they are constantly failing?

How many nox sensors are on this engine, 2 or 3?

Can the nox sensors be deleted/coded out?

 

[alexanderfoti]

There are lots of threads on this, but condensed.

1. Original from the factory nox sensors are rubbish and fail after 2-3 years.
2. New Nox sensors were on backorder for ages during COVID and so they released a new version after a few years.
3. This new version requires a software update. If you do a software for any other reason, you need the new Nox sensors.
4. Queue lots of garages fitting 1 of 2 updated sensors, giving same issues, as no software update done or
5. Garage doing software update for other reason, and then causing nox sensor.

 

[fabes]

Alex, for the OP's benefit, apart from the sellers (potentially incomplete) service records, is there anyway to know if the nox sensors have been replaced with the most recent best ones via a code reader?

Or would it be only on a ramp?

 

[alexanderfoti]

If the code reader can read the hardware number then yes as it will mach the part number of the newer.

 

[Srdl]

Am I missing something here? OP wants a petrol engine so surely NOx sensors aren't going to be a problem? Or do I need to worry as I've got a M276 engine as well!

 

[alexanderfoti]

Also fitted on petrol engines, but not intrinsically linked to an adblue system, so the only symptom is a check engine light.

 

[fabes]

And they do fail
And cost a bob or two

I had both go on my E350 (once covered by the selling garage) and they've both been done on my E400 before I bought it. Both petrol M276's

Once replaced I had and have had no issues and iirc, the only symptom I had was an EML, no limp mode or the like on the 350 both times

Great engine otherwise.....