[herrbrahms]

Last October, my better half and I took the longest daytrip ever to see a solar eclipse, about 1100 miles total. We had to get home within 24 hours to take care of animals.

Anyway, 100 miles into the trip, I got the dreaded 1000 mile DEF countdown and groaned. It was questionable whether we'd make it home before the car went into no start, and since we were eclipse chasing through iffy weather in the desert, I didn't want to have to deal with it any longer. Now, what I should have done was to go into Walmart, buy a jug of DEF and a funnel, and take 20 minutes to top up. This is not what I did. What I did instead was to fill DEF from a truck stop nozzle. It eventually made the countdown go away.

This quickly proved to be a mistake when less than 100 miles later, I got a CEL. Pulling over and reading the code, I got an 805256 "echo sensor" fault from the SCR tank, in addition to the 8051B5 "return pump outside permitted range" code which had been there for years. I have fought the echo sensor code on and off over the past year and 12,000 miles. Sometimes I reset it and it stays gone for a month or two, but it always comes back. I'm on the stock tune and have no interest in spending over $1000 for a new active tank.

With my annual weather window for service coming to an end over the next month, I am lifting the rear of the car to pull the shocks out and replace the bump stops. The shocks themselves are fine. Did I mention that I often use this car like an F-250, pulling a trailer across the country and occasionally filling it with heavy loads? Yeah, I do that. Anyhow, while the rear is lifted, I thought about a last ditch effort to pull the active tank, wash it out in the shower a few times, give it a final rinse with distilled water, then reinstall and see if my problem is gone. My theory is that crystals or crud have contaminated what might otherwise be a working sensor, so why not clean it?

So here are the questions. 1. Does this sound plausible? 2. Has anyone pulled an active tank before and tried to bring it back from the dead? 3. Are there any surprises I should expect? Last year I walnut blasted my intake ports and powerwashed my manifold among other chores. I've replaced my own hard coolant pipes on my other car, an E46 330Ci, but the F30 N47 I find less intuitive. Layout can be tricky, hose clamps are a PITA, NVH insulation is cumbersome, and I'm generally wary of getting too far ahead of myself with this car in a way that I'm not with my E46.

That's why I'm asking you fine folks for advice instead of just blundering ahead. I don't want to break shtuff. Prior planning prevents poor performance.

I would also be interested in exploring software delete of the SCR system as well as EGR which already coked up my intake once. I've looked for tuners in both Seattle and Portland, but it seems that everyone lives in fear of the gubmint now and nobody will advertise their services. I've dealt with the emissions controls on this car for 10 years now, but now it's time to change things up to focus on reliability. I meticulously maintain my car, and I can't be having it act up on me in the middle of Wyoming.

Thanks!

[cezar22]

Man I pulled the tank when I did the delete and I could not even fathom how it would go back together. I broke a lot of stuff just trying to get it out. Also it dumped piss on me which I will never forgive.

EDIT: Missed where you were considering the delete. DO IT. Yours is pre-lci so you can do it without shipping the ECU for an unlock. The only good thing about pre-lci. Do the legwork and sleuthing. it's worth it.

[F31_King]

I had a failed level sensor in the active tank that caused the countdown.
With a used active tank (look on eBay) in hand, I replaced the one in my car. Had been working like a charm since. If you know how to turn a wrench and have some basic BMW orientated tools, you can replace the tank.
You can use ISTA+ to diagnose further if wanted.

However, if you want to delete it, there are several options these days. I would suggest checking out the diesel BMW Facebook page to explore the options

For example: https://www.facebook.com/share/p/JKzdq3n657xAqNcs/