[W37V]

Got Exhaust fluid incorrect error message. Now I have less than 190 miles remaining before no start condition. I really didn't think this was an issue f15, but i guess it is. I only used bmw def fluid.

Based on my research it could be either of following:
NOX sensor before 13628589846 - $303
Nox after 13628589844 - $303
Metering unit 18308514448 - $280
or def tank - $1400

Does anyone know if there are cheaper alternatives to above? I think nox sensors are made by continental. I have no clue where to begin. Replace parts in hope to get it fixed or just get a tune and delete it?

Somewhere, I read that I should try to drain all the def and replace it in hope it would clear the error. The worst part is, the no start error is hard coded, so it can't be erased unless all the conditions are met (issue is fixed).

Codes I got:
Fault Code: 26FD00
Fault Explanation: Reducing agent dosage, long-term adaptation:
adaptation value too high
Fault Code: 2C4E00
Fault Explanation: DeNOx system, plausibility: System error or bad reductant recognized quality
Fault Code: 29FB00
Fault Explanation: DeNOx system, warning and Abschaltszenario:
warning level 1
Fault Code: 29FC00
Fault Explanation: DeNOx system, warning and Abschaltszenario: warning level 2
And
FF26FD - No code description

Any advice would be appreciated.

Edit: So, this issue might be covered by BMW warranty. It seems that BMW guarantees some emission components for 80k miles or 8 years. Since I am under 80k, this might be covered. Hopefully it is. Otherwise, throwing parts at it it is.