HELP! > CEL P20E8 Generic Permanent

RebornS14 · 02-13-2019, 01:31 AM

i have a 2011 335d with about 110k miles

a while back i bottomed out on a dip and not long after i got a check engine light. my scanner displayed P20E8 - Reductant Pressure Too Low

wasn't sure what it was but not after that i noticed my rear bumper looking strange and realized it was DEF leaking and the air diffusing the fluid from under my car all over my bumper. and of course soon after that i got the warning. XXX miles before my car would start due to low DEF.

long story short i finally got around to taking apart my trunk and exhaust to examine the damage. found a mess above the tank due to the DEF pump nipple that connects to the hose going to the SCR broken off. basically my pump was just spraying out all on top of the tank and down. and i figured the CEL was due to the hose being disconnected. i was able to remove the nipple from the hose and ordered a new pump (OEM Bosch) and replaced it.

i had filled DEF before i did all this thinking it would just reset and allow me to drive more but no, it didn't raise my count or reset it which is why was forced to fix it.

So i drove it around figuring everything would be fine now but eventually the code came back. at first it was just pending. then came on later. went back and decided to check the hose. thinking maybe it got clogged due to the crystallized urea. i disconnected the line at the SCR and pump and blew compressed air through it. i saw some DEF come out the other end so i figured it was clear enough.

put everything back together and reset the code, drove around again. same thing. code pending and came back on. now im puzzled. i took everything apart again to examine everything. maybe i missed something, left something unplugged. did a full inspection. couldn't find anything so i went online and found others who had issues with their SCR clogged. today i took everything apart again to examine my SCR and it was actually pretty clean. no clogs or crystallized urea. again double checked more stuff. rechecked to make sure the o-ring was seated properly on the pump, i had cleaned off the stains from the DEF so i didn't see any new leaks. i chased the DEF line from the tank to the SCR looking for leaks and found everything intact.

put everything back together and now when i delete the code, it comes right back on as P20E8 Generic Permanent.

Now i don't know what to do. Do i need to code something out when you replace the DEF pump? what am i doing wrong? can't seem to find much online about this code for the 335d so i figured i'd post my story here and hopefully find a tech or someone who's tackled this issue before.

Finnyfam60 · 05-07-2019, 09:37 PM

RebornS14 I have the same code thrown, and the same white/clear residue on the rear of the vehicle... havent had time to dig into yet though.... have you solved your issue??

Thecastle · 05-08-2019, 07:34 AM

if you actually want to fix this, you should get a BMW code scanner to identify the specific issues. This code is a generic OBDII code and won't say what exactly is wrong or provide the BMW extended coded.

Carly is a good option, as well as others

To my knowledge there is no way to "code" (change a paramater in the DDE) out the SCR. You have to replace the software in the DDE to remove this function which is possible with a tune. JR/BPC offer stock hardware EGR, DPF and SCR removal tunes.

02-13-2019, 01:31 AM	#1
RebornS14 New Member 6 Rep 16 Posts Drives: E90 335D Join Date: Oct 2016 Location: Cerritos, CA iTrader: (0)	HELP! > CEL P20E8 Generic Permanent i have a 2011 335d with about 110k miles a while back i bottomed out on a dip and not long after i got a check engine light. my scanner displayed P20E8 - Reductant Pressure Too Low wasn't sure what it was but not after that i noticed my rear bumper looking strange and realized it was DEF leaking and the air diffusing the fluid from under my car all over my bumper. and of course soon after that i got the warning. XXX miles before my car would start due to low DEF. long story short i finally got around to taking apart my trunk and exhaust to examine the damage. found a mess above the tank due to the DEF pump nipple that connects to the hose going to the SCR broken off. basically my pump was just spraying out all on top of the tank and down. and i figured the CEL was due to the hose being disconnected. i was able to remove the nipple from the hose and ordered a new pump (OEM Bosch) and replaced it. i had filled DEF before i did all this thinking it would just reset and allow me to drive more but no, it didn't raise my count or reset it which is why was forced to fix it. So i drove it around figuring everything would be fine now but eventually the code came back. at first it was just pending. then came on later. went back and decided to check the hose. thinking maybe it got clogged due to the crystallized urea. i disconnected the line at the SCR and pump and blew compressed air through it. i saw some DEF come out the other end so i figured it was clear enough. put everything back together and reset the code, drove around again. same thing. code pending and came back on. now im puzzled. i took everything apart again to examine everything. maybe i missed something, left something unplugged. did a full inspection. couldn't find anything so i went online and found others who had issues with their SCR clogged. today i took everything apart again to examine my SCR and it was actually pretty clean. no clogs or crystallized urea. again double checked more stuff. rechecked to make sure the o-ring was seated properly on the pump, i had cleaned off the stains from the DEF so i didn't see any new leaks. i chased the DEF line from the tank to the SCR looking for leaks and found everything intact. put everything back together and now when i delete the code, it comes right back on as P20E8 Generic Permanent. Now i don't know what to do. Do i need to code something out when you replace the DEF pump? what am i doing wrong? can't seem to find much online about this code for the 335d so i figured i'd post my story here and hopefully find a tech or someone who's tackled this issue before.
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05-07-2019, 09:37 PM	#2
Finnyfam60 Registered 0 Rep 1 Posts Drives: 2011 335d sport Join Date: Mar 2019 Location: Nor Cal iTrader: (0)	RebornS14 I have the same code thrown, and the same white/clear residue on the rear of the vehicle... havent had time to dig into yet though.... have you solved your issue??
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05-08-2019, 07:34 AM	#3
Thecastle Major 307 Rep 1,146 Posts Drives: F10 550i Join Date: Apr 2015 Location: Houston, TX iTrader: (0) Garage List 2020 BMW M340i [0.00] 2019 RAM 3500 [0.00] 2020 BMW X3 [0.00] 2016 BMW 550i [0.00] 2000 Ford F450 7.3l ... [0.00]	if you actually want to fix this, you should get a BMW code scanner to identify the specific issues. This code is a generic OBDII code and won't say what exactly is wrong or provide the BMW extended coded. Carly is a good option, as well as others To my knowledge there is no way to "code" (change a paramater in the DDE) out the SCR. You have to replace the software in the DDE to remove this function which is possible with a tune. JR/BPC offer stock hardware EGR, DPF and SCR removal tunes.
	Appreciate 0 Quote