NOx Sensor Advice

[magpiemalemerc]

Same as Chernobyl. This has gone deep.

I remember my tyre wore on the outside I took mine to a Garage in Wellingborough that sorted my tracking alignment via the hawkeye laser
I wear mitchelin Cross climate on my C-class now perfect tyre.

 

[tombell]

Mercedes Quote with Part Numbers for replacing Nox Sensors on 2012 ML250 TOTAL £ 1,620.96

Labour 3.8 HOURS £385.70

MA166 520 02 23 NOISE CAPSULE £ 88.50

MA000 905 35 03 104A05 NOX SENSOR £417.00

MA202 490 08 41 108C05 CLAMP £ 10.00

MA000 492 08 81 101D04C SEAL RING £ 5.75

MA000 492 08 81 101D04C SEAL RING £ 5.75

MA202 490 08 41 108C05 CLAMP £ 10.00

MN910143 008 006 102D06C HEXALOBULAR BOL £ 1.40

MN910143 008 006 102D06C HEXALOBULAR BOL £ 1.40

MA000 905 36 03 104A13 NOX SENSOR £379.00

MA002 995 49 02 107E09 PIPECLAMP F EXH £ 46.30

NET £1,350.80
VAT £ 270.16
TOTAL £ 1,620.96

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Friday at 8:33 PM

 

[JamesPGUK]

NOx sensor being done after 4 month wait for parts.

 

[tombell]

DRILL A SMALL 3MM HOLE AT THE LOWEST POINT Taken from an earlier response by UKY.................

I had a talk with one of my friends working as a MB mechanic and he happend to mention NOx-sensor failures,
particularly the rear one. One of his customers have had repeated failures and replacements.
Eventuallay, he learned that the problem was accumulation of condensated water in the (cold) exhaust system

When driving, the NOx sensor is heated by its supply voltage, and when the driver makes a sudden movement
the cold water hits the sensor and destroys it.

The advice from MB support was to drill a small hole ~3mm at the absolute lowest point
of the exhaust system where water could accumulate. Then as the next step, the car should be driven
and forced to make a catalyst rejuvenation cycle, burning away any residual water in the system.

 

[magpiemalemerc]

I have had a NOX sensor problem.. booked it in got it checked part was ordered.. but cancelled later 4 days later as the engine light went off.. weeks later the light came back on.
The light has been on for weeks but after a run to Poole and back the light has gone off actually went off after the 2nd day in Poole.
Coming back it has stayed off... my reasoning is the car being diesel doss not do well on short journeys.... we all know it takes a while to get a car up to temp but giving the car a good run over 150 miles has seen the light go off on the dash... another mile busting journey coming and I will see if it stays off... I gave the car a good stretch sports plus and sports mode.
When I bought the car the wife used it 50miles away hence the diesel but now with covid etc working from home the car is idle apart from local runs..... so if you go for a good 150 - 200mile run maybe it will cure the problem ?? These cars are made to run and run like work horses not be looked at but this is my experience not yours..... everyone one is different ..

 

[tombell]

I'm just going to drill a 3mm hole at the bottom of the Cat

 

[Deleted member 65149]

I'm just going to drill a 3mm hole at the bottom of the Cat

That doesn’t sound like a good plan to me. Isn’t there a danger of damaging the materials inside?

 

[tombell]

According to UKY................. It should be OK to do this

"I had a talk with one of my friends working as a MB mechanic and he happend to mention NOx-sensor failures,
particularly the rear one. One of his customers have had repeated failures and replacements.
Eventuallay, he learned that the problem was accumulation of condensated water in the (cold) exhaust system

When driving, the NOx sensor is heated by its supply voltage, and when the driver makes a sudden movement
the cold water hits the sensor and destroys it.

The advice from MB support was to drill a small hole ~3mm at the absolute lowest point
of the exhaust system where water could accumulate. "

 

[Deleted member 65149]

According to UKY................. It should be OK to do this

"I had a talk with one of my friends working as a MB mechanic and he happend to mention NOx-sensor failures,
particularly the rear one. One of his customers have had repeated failures and replacements.
Eventuallay, he learned that the problem was accumulation of condensated water in the (cold) exhaust system

When driving, the NOx sensor is heated by its supply voltage, and when the driver makes a sudden movement
the cold water hits the sensor and destroys it.

The advice from MB support was to drill a small hole ~3mm at the absolute lowest point
of the exhaust system where water could accumulate. "

I’ll confess that I don’t know exactly where the NOx sensors are mounted, but I thought it was in the exhaust pipe itself. If water is gathering in the cat, I would have thought it unlikely to flow through and onto the sensors. But if water gathers at a low point on the pipework it would be easy for it to slide along to the sensors. But I don’t know, I’m just guessing.

 

[tombell]

I'm pretty sure the Nox Sensors are either side of the Cat. One on the exhaust system before the Cat and another on the exhaust system leaving the Cat. I'm guessing that if too much ADBLUE liquid is gathering in that area it will probably affect the Nox Sensors

 

[grober]

Either side of the selective catalytic reduction unit = SCR------ I believe an exhaust temperature sensor is also involved meaning the adblue system is inoperative till it theoretically reaches operating temperature??

 

[mercmancdi]

got this for mine but wrong one for my model , very hard to get lots on back order.

 

[tombell]

Either side of the selective catalytic reduction unit = SCR------ I believe an exhaust temperature sensor is also involved meaning the adblue system is inoperative till it theoretically reaches operating temperature??

I am contemplating drilling the 3mm hole in the Cat as I am really worried. It cost over £1,500 to have new Nox Sensors fitted recently and i don't want it to happen again. Especially since Merc took over a week to get the new sensors.
I also understand from a previous post that there are some pattern Nox sensors available that have been fitted by others on this forum. Do you know the name of the manufacturer?

 

[arcton114]

Mine were replaced completely out of the blue FOC on my old W205 when it went in for an unrelated job, was a bit miffed at the time because they had no conversation to discuss this,

The more I read about the potential cost the less miffed I am,

I would avoid drilling a hole in the exhaust mind, as far as I’m aware the system is mild steel and will start to corrode over time with water ingress, ultimately pressure from inside the system blowing out of a small hole will only make the hole bigger, then you cars farting

I would reccomend doing it properly at the very least, drill a 5-6mm hole and tack weld a small stainless M3 nut or even washer over or in the hole then seal with exhaust paste, still not the best idea though in my opinion

 

[zena123]

arcton wrote: I wd avoid drilling hole in exhaust (mild steel .. will corrode .. water ingress ....do it properly: drill 5-6mm hole & tack weld small stainless M3 nut/washer over or in the hole, seal w exhaust paste (still not the best idea though in my opinion)
Has anyone done this & found it works ... long-term ?? Tia

 

[zena123]

Magpiemalemerc wrote: giving the car a good run over 150 miles has seen the light go off on the dash
Sustained 70mph ? or will 50mph do .... motorways generally having speed restrictions nowadays .... Asking, as I have EML/nox sensor issue &
cd try a trip this w/e ... Anyone else find it works ?? tia again