VEMO/Vierol Nox Sensor Replacement

[JN52]

Hi all,

 

Just before Christmas my engine management light came on in my A6 Allroad C7. I took it to a garage and they ran a diagnostic and told me it was a Nox sensor fault...and then told me the cost of the repair...!! I've managed to not really drive too much since then and a friend put his diagnostic tool on for me at the weekend to show me the codes. It's coming up with the following:

P067100 - Cylinder 1 Glow Plug Circuit (I'm going to change all 6 glowplugs)

P229E00 - NOx Sensor Bank 1 Sensor 2 - Circuit

P229E00 - NOx Sensor Bank 1 Sensor 2 - Circuit

P229E00 - NOx Sensor Bank 1 Sensor 2 - Circuit

P22A700 - NOx Sensor Heater Sense Bank 1 Sensor 2 - Circuit Range/Performance

I've had a look online for replacement NOx sensors and they all seem to be approx. £500, except one on Auto Doc which is VEMO part supposedly on sale from RRP of £646 down to £244. The further information on Auto Doc says the manufacturer is Vierol from Germany

This is a link to the part:  

https://autodoc.co.uk/vemo/21494755

Now...is this too good to be true? I've googled VEMO and get results that it is a Chinese brand, but the VEMO/Vierol site seems to say it is German made and to OE specs...does anyone know the truth?

Thanks in advance!

Nick

[Stevey Y]

4 hours ago, JN52 said:

Hi all,

 

Just before Christmas my engine management light came on in my A6 Allroad C7. I took it to a garage and they ran a diagnostic and told me it was a Nox sensor fault...and then told me the cost of the repair...!! I've managed to not really drive too much since then and a friend put his diagnostic tool on for me at the weekend to show me the codes. It's coming up with the following:

P067100 - Cylinder 1 Glow Plug Circuit (I'm going to change all 6 glowplugs)

P229E00 - NOx Sensor Bank 1 Sensor 2 - Circuit

P229E00 - NOx Sensor Bank 1 Sensor 2 - Circuit

P229E00 - NOx Sensor Bank 1 Sensor 2 - Circuit

P22A700 - NOx Sensor Heater Sense Bank 1 Sensor 2 - Circuit Range/Performance

I've had a look online for replacement NOx sensors and they all seem to be approx. £500, except one on Auto Doc which is VEMO part supposedly on sale from RRP of £646 down to £244. The further information on Auto Doc says the manufacturer is Vierol from Germany

This is a link to the part:  

https://autodoc.co.uk/vemo/21494755

Now...is this too good to be true? I've googled VEMO and get results that it is a Chinese brand, but the VEMO/Vierol site seems to say it is German made and to OE specs...does anyone know the truth?

Thanks in advance!

Nick

Hi most of these parts are made in China under licence and to OE spec, therefore it more than possible they will perform as required but may well have a shorter lifespan.

Steve.

[JN52]

13 minutes ago, Stevey Y said:

Hi most of these parts are made in China under licence and to OE spec, therefore it more than possible they will perform as required but may well have a shorter lifespan.

Steve.

When you say a shorter life span, how do they roughly equate...will I be replacing it in a year, or will it last 5 years for example?

[Stevey Y]

22 hours ago, JN52 said:

When you say a shorter life span, how do they roughly equate...will I be replacing it in a year, or will it last 5 years for example?

Hi at average milage normally about 4 years, I only say this as I replaced one on my cab which lasted 2 years but if you consider that was 80k and was hard milage, stop start and short journeys, I can honestly recommend giving the car a dose of Wynns EGR cleaner every couple of months that keeps the sensors soot free and adds to their longevity.

Steve.

[JN52]

3 hours ago, Stevey Y said:

Hi at average milage normally about 4 years, I only say this as I replaced one on my cab which lasted 2 years but if you consider that was 80k and was hard milage, stop start and short journeys, I can honestly recommend giving the car a dose of Wynns EGR cleaner every couple of months that keeps the sensors soot free and adds to their longevity.

Steve.

OK thanks. Nice tip on the cleaner!

I took the plastic under tray off earlier to try and get in at the Sensor parts and find the part code just to double check fit. This is what I saw...i assume the actual metal plate part is under the metal heat shield?? Or am i not seeing it properly...or is this actually a different part!? 

Red circle is what is accessible after taking the plastic tray off, blue circle is where im assuming the part is under the heat shield??

 

 

[JN52]

Second photograph of the underside showing the sensor going into the exhaust and the blue circled area from the above post bottom left centre.

[Stevey Y]

On 2/6/2025 at 9:01 PM, JN52 said:

Second photograph of the underside showing the sensor going into the exhaust and the blue circled area from the above post bottom left centre.

Hi the problem is thats the one thats likely to be a bit of a fight to get out as they corrode in, plenty of plus gas and some patience should prevail, bank 1 sensor 1 is a lot easier as its up top, thats the one I replaced.

Steve.

 

[JN52]

OK , thanks for the heads up! Is the bit I've circled in red the same as the product I've linked, Just the OEM part so looks different!? Or is the actual part i need to remove from the car (metal plate with plugs attached) underneath that heat shield!? Aware ofcourse that the actual sensor in the exhaust also requires removal. 

[Stevey Y]

40 minutes ago, JN52 said:

OK , thanks for the heads up! Is the bit I've circled in red the same as the product I've linked, Just the OEM part so looks different!? Or is the actual part i need to remove from the car (metal plate with plugs attached) underneath that heat shield!? Aware ofcourse that the actual sensor in the exhaust also requires removal. 

Hi the red circled bit is the part you want, just wondering if you landed on the part you intended to buy using the OE number?, if not I would definitely go to the LLL carports catalogue, enter your VIN and then go fishing with the part number, as for the picture on the other site that could be generic they tend to do that on these sites.

Steve.

[JN52]

So looking in the engine bay, there is a NOX sensor that looks the same as the parts I've found online (and has part number 4G0907807S) when looking for Sensor 2 (photos below). It goes into the exhaust at the location circled in blue (cyan?? lol). However, when I've been looking for NOX Sensor 2 the part number appears to be 4G0907807AJ, but what I'm looking at under the car (in red circle in post above) appears to be a totally different part...possibly an exhaust temperature sensor from some googling! Im assuming though that the part in the engine bay is Sensor 1 and not Sensor 2, and as your comment above Steve the one I've been looking at before underneath the car is the correct NOX Sensor 2 (which is what i have a fault code for!)!? In which case does anyone have any idea where I can find a replacement Sensor 2 as seemingly all I can find is replacements for Sensor 1  😂 🙈

[JN52]

Looking on LLL I think the sensor I posted originally is definitely the exhaust temperature sensor...

 

The cable coming off and electrical connector definitely look the same to me (see above first post above with photos), but its the only sensor I can see after the Catatlytic converter 🧐

 

So now I'm very confused and will have to get the car back up on axle stands tomorrow to have another good look for the NOX sensor...Is the answer potentially that there is only 1 sensor 2, and I'm looking on the wrong side?? My code was for Bank 1 (RHS, UK drivers side) but is the answer that the there is a temp sensor on the RHS and a NOX sensor on the LHS!?

Edited February 15 by JN52

[JN52]

So...mystery solved! Turns out when you watch a VW Sharan video to find a part on an Audi A6...not everything is in quite the same place 😂! I was looking about 2ft too far forward! The NOX sensor 2 for the A6 Allroad is quite far back from the catalytic converter and where the pipes become one again (so not sure why it lists it by bank on the fault code, although maybe it has to list a bank by default 🤷‍♂️). The sensor electronics plate is under the rear most underbody panel, on left of the car (UK passenger side), which comes off with 4 Torx screws. I'm yet to actually try to get the sensor out of the exhaust but did manage to take the plate off to confirm the part number. Photos below!

 

Edited February 16 by JN52