Help Required- NOX sensor

[Kenny32]

Looking for a bit of advice. My 2012 BMW 1 series Msport (72000 miles) just failed its MOT on emissions as the lambda was too high. The garage said they ran diagnostic and the NOX sensor needs replacing. This is quite an expensive job (£620 including parts, labour, VAT ect). I’ve said I’ll have a think and took the car home and ran my own OBD diagnostic tool on the car. My concern is no error codes have come up. I took the car to another garage for an emissions test and they did confirm the lambda is too high to pass MOT.

My question is, is it possible for the NOX sensor to be causing the emissions test to fail when it is not showing up as an error on my diagnostic tool?

 

 

[Greydog]

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