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      05-25-2023, 03:28 PM   #21
AndrewC1989
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Drives: 2015 328d xDrive
Join Date: Aug 2010
Location: NoVA

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Quote:
Originally Posted by rparnel1 View Post
My 2014 328d with 110,000 miles also had the "incorrect exhaust fluid - no start in 200 miles" warning

Used Bimmerlink to scan for fault codes and had these:
28EB00: NOX sensor in front of cat, plausibility, NOX signal too slow
26F500: DENOX system, efficiency, too low range 1
26FD00: Reducing agent dosage, long term adaption, adaption value too high
2C4E00: DENOX system, plausibility: system error or poor reducing agent quality
29FB00: DENOX system ;warning and switch off scenario, warning level 1
29FC00: DENOX system waring and switch off scenario, warning level 2

DEF fluid tank is full and fluid is not old. Also have white coating on exhaust tip. I track the DEF usage and noticed that it has been erratic over the past year. This recent instance had it using 3 or 4 times as much for a given mileage period. Also had EGR recall done about 750 miles ago; dont know if that has any relevance

These were my initial conclusions:

1. The injector/valve is dirty and causing poor injection. Never been cleaned
2. Pre-cat and/or post/cat NOX sensors are faulty. They are originals
3. The DEF fluid being actually incorrect or low quality is rarely the root problem.
4. Other SCR system problems

The NOX sensor warranty is extended to 120k miles.

Solution: took the car to dealer where they replaced both Nox sensors under warranty, but still had the warning. They replaced the catalytic converter, which resolved my issue. $3400
$3400?! Hell no, I'd have gotten a used one on eBay.
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