NOx sensors issue

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Cornishandy

New Member
Joined
Nov 28, 2019
Messages
1
Location
Cornwall
Car
Mercedes C Class 250 Sport
Afternoon all,

Just after some advice please. I own a C Class 250d 2015 model, 89,000 miles. Owned for 18 months, extended warranty has expired.

The car has been a dream until last weekend. Engine management light on - no issues with the car, drives fine.

Took it in to my local indy - he ran a Xentry diagnostic and concluded that both NOx sensors needed replacing. He said they do loads of these, really common problem but unfortunately pricey to sort. He recommended i call Mercedes main dealer and tell them the problem and see if MB UK will assist financially. If not go back to him and he will price up/replace.

So I emailed Inchcape, Reading where i bought the car - they replied promptly saying the car needs the SMPC760 Update Engine Control Unit Software - as part of this they will test the NOx sensors and replace free as part of the recall.

So it seems like a no brainer to me? However having come from a VW Passat where VW did a software update on that and the car was never the same again I'm sat here wondering what to do..................??!!

Any help / comments appreciated please.
 
Afternoon all,

Just after some advice please. I own a C Class 250d 2015 model, 89,000 miles. Owned for 18 months, extended warranty has expired.

The car has been a dream until last weekend. Engine management light on - no issues with the car, drives fine.

Took it in to my local indy - he ran a Xentry diagnostic and concluded that both NOx sensors needed replacing. He said they do loads of these, really common problem but unfortunately pricey to sort. He recommended i call Mercedes main dealer and tell them the problem and see if MB UK will assist financially. If not go back to him and he will price up/replace.

So I emailed Inchcape, Reading where i bought the car - they replied promptly saying the car needs the SMPC760 Update Engine Control Unit Software - as part of this they will test the NOx sensors and replace free as part of the recall.

So it seems like a no brainer to me? However having come from a VW Passat where VW did a software update on that and the car was never the same again I'm sat here wondering what to do..................??!!

Any help / comments appreciated please.
I've had the update done on my 2018 C Class - absolutely no problem since, although some on here have had a different experience. My feeling is that the problems have been mainly with E Classes where they don't engage 9th until above 70. My gut feel is that mine is slightly readier to change down to 8th on the m/w, but I have no hard evidence of that.

The bottom line is that you don't want to shell out £1200 on NOx sensors so you need to get it done!

Incidentally, I recently saw 65.2 MPG on a trip from Keynsham to Bromley....until the sat-nav took me through Central London! My average MPG through the summer has been 50.4.

Ernie
 
I've had the update done to. No ill effects at all. In fact if day it was better than before. No performance loss, better mpg and no issues with gear changes. Mines a c220d for info though - 2016, 27k miles. Mercedes said that it will prevent the nox issue but if there were problems in the future this would mean Mercedes covered the costs. I'm not naive, I suspect that's more flim flam than fact, but without the update they definitely would ignore me I'm sure.
 
I have an E220d and nox sensors set off Engine management light, so I took to Mercedes specialist and they said try update first to see if that helps resolve issue. Had it done and the car was like it had been injected with redbull, the acceleration was instant, feather light and very sensitive and it was so quick to reach higher speeds.... then the EML came back on and over the next week and a half i felt it lose most of that extra oomph, also I did notice before the fuel reserve would come on around 90 or so miles, but after the update it came on with 78 miles to go. Not sure what it did but now it’s back to 98.
 

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