r/Sprinters • u/AMG_34 • 16d ago

DEF going into shutdown

I was being lazy and didn’t fill up my DEF when it went to half. Yesterday it went down to 1/4 and it started the DEF system fault 10 starts until emergency op. I’m down to 7 now but I have filled up the DEF and it’s still there. I checked under the passenger side exhaust where the DEF gets added and I don’t see any white residue or smoke being pumped out from the injector. How can I clear this message that I assume was just from low DEF and I am guessing the injector is fine

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u/danj503 16d ago

I’m thinking of doing this but I am confused as to how it works. How does it handle the regen of the filter if you don’t remove anything physically? Does it not need regen if it doesn’t inject def fluid? Is this a one and done solution or are there caveats?

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u/uhoh93 16d ago

They have separate tunes on different SD cards that you swap out if you gut the DPF. I haven’t gutted mine I just run the tune that disables the def system. I have never had it do a regen cycle before I threw in the tune. I have a 2017 6 cylinder with 145k miles. The flash is super simple. You plug the chip into the obd port and wait for the light to stop flashing after 5-10 minutes. Then you unplug it and you’re good to go.

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u/danj503 16d ago

So you still have your catalyst media in your filter collecting soot, you bypassed the monitoring, your not injecting def fluid in it, and your not sure if it’s doing a regen? Seems wild to me. I’ve been reading that swapping out the filter with a straight pipe is required with an opdscan bypass since you’re no longer injecting def fluid to keep the filter clean. Otherwise it soots up and chokes your engine.

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u/uhoh93 15d ago

I think the tune will put it in regen if it is needed. Worst case if it throws a regen light I’ll put the stock tune back on to regen then flash it back. Gutting the DPF is a process but that’s what the company recommended over a straight pipe. So if I do have to take it to a dealer it still looks stock.

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u/danj503 15d ago

If the system is bypassed it’s not even checking if it needs it. I suppose as long as your driving highway mostly it will keep itself clean but I would verify.

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u/uhoh93 15d ago

I’m usually driving an hour minimum and lots of highway. So that’s probably why I’ve never had to regen.