Nox sensor situation - i changed it last year and now mercedes are offering a replacement

[platforminc]

Hi All.

I had a situation where my nox sensors needed replacing last year, during the process of changing it, the sensor threads got stuck on the bung and the sensors couldn't come out. The garage changing it had to use heat to take out the old sensors, and in the process the threading got damaged. The solution was to weld a new bung onto the exhaust and have the sensor go into the new bung. The bung was welded flush on the exhaust.

The sensors are OEM part and not mercedes branded, the next day after changing them (2 sensors), the warning light came on again and I came on the forum to ask for advice. I was told that the software on the car needed updating to work with the sensors. During a routine visit to Mercedes, it turns out that there was a recall on the vehicle and the car software needed updating, I took it to mercedes about 2 months ago, and they updated the software but didn't clear the nox sensor error, during that visit I was told that they will replace the nox sensor for free when they next have it in stock as it appears to be a common failure. The funny thing is that last year when I called them to ask if they would replace it for free, they said NO.

The sensors are due to be changed by mercedes next week, however I am concerned about 2 things.

1) The warning light is still on the dash, but I can clear this. it usually comes back after a long motorway trip.
2) The welded bung on the exhaust, I don't know what they will say about this. It also got me thinking, if that was mercedes that had to take out the first sensors and the thread got damaged due to the sensor being stuck, would they ask me to buy a complete exhaust ?


Are there any precautions I should be taking or if I get the dreaded call about non original sensors being used, and they would cease work on the vehicle.

 

[Marco247]

Hi
Down Stream went on mine and up popped the engine management light.
A sorry tale but MB not interested (too old 2017) ordered a new one off them, no stock and dont know when they are coming in, maybe a month, maybe a year, maybe never was the reply!
On fleabay I went and found a listing for a new Merc sensor, too good to be true surely?
It came all good and originally boxed and £299 all in.
Fitted it easily with a £12 nox sensor spanner also off ebay.
The seller of the sensor stated the engine management light would go out in about 100 miles all by itself with no intereference, no going into the garage ,no nothing, (ye righto.......) the total opposite of what MB stated,they stated it must be re coded to work.
Off went the light ,100 miles in 4 days it went out! A cheer was heard for miles around.
All it left was a stored fault code which was easily cleared with cheap OBD reader.
In answer to your post Id say
1) Will do if its buggered
2) Say nowt and see what they come back with, cant see it being an issue as some sensors do need heating up and thread busts getting them out (luckily not mine) so what are folk meant to do other than repair?

 

[bladecrazy]

I got my pair of sensors off ebay after mercedes main dealer said no good will and 1k if they changed them, got 2 for £500 off ebay then sold it before the adblue tank went!.

 

[platforminc]

I got my pair of sensors off ebay after mercedes main dealer said no good will and 1k if they changed them, got 2 for £500 off ebay then sold it before the adblue tank went!.

When you changed it with the one you got, did the warning light come on again ?

 

[bladecrazy]

no more warning lights , my nephew fitted them with no problems.

 

[mioba]

1 - cars are clever, if there is a fault there is a fault
2 - TRICKY. I can imagine merc saying non original sensor and if its welded - you can forget them trying to repair.
These recalls cost millions and where they can negate costs they will.

Just my tuppence with dealers. Please keep us updated.

 

[Botus]

read some other posts...

There are various iterations of ecu software that work (kind of) with various hardware iterations

the correct, long term, secret relaibility bugs removed from the ecu, and finally emission legal fix. is mk3 NOx sensors and three software updates

I expect you will come unstuck with a modified set up

 

[Botus]

the biggest issue sorting it all out so it works in the end, is the Engine ECU is full of deliberate bugs - they got found out - and wrote a good one - but half the idiots don't want it and even when you do - you need the latest DFP sensor and Mk3 NOx sensors or you can't fit the fault free map or sort the corresponding SCR update