BMW Fault Code 4804 - Reducing Agent no reducing agent pressure build-up possible

135i_vs_ · 03-27-2017, 08:56 AM

Has anyone had and fixed this code before?
I'm not sure if the problem is a part covered by the emissions warranty.

I'm at 99,xxx.

Thanks,

135i_vs_ · 03-27-2017, 09:10 AM

From reading a post from another forum, it might be the supply module?

Is this part difficult to change? I never even took a look near the active tank area.

http://www.realoem.com/bmw/enUS/show...28#16197244137

kpm · 12-07-2021, 07:48 PM

Original owner of stock 2009 335D with 222k kms(138k miles)
Outside of recall items, no previous issues since new with emissions system.
Having lost faith in my local dealership(useless beyond routine maintenance) and that is being kind, I began to self service in 2020. With COVID 19 et all, having retired and my wife working from home, my D lacked exercise and DEF was getting stale.
Early this Fall:
"No Start 1600 kms" light,Code 474C Exhaust Fluid warning as well as Code 4804 Pressure control SCR, overpressure fault
Refilled only the passive tank with DEF" with hope to using up the stale fluid in the active tank. No start" light cleared after a few days and trips

Removed the DEF metering valve and though dry with no visible crystal buildup like othes seen on this forum, I rinsed with distilled water replaced and cleared errors. Error code 4804 has never returned.

03-27-2017, 08:56 AM	#1
135i_vs_ Captain 75 Rep 697 Posts Drives: M5, 135i, 335d, F10 550xi Join Date: Sep 2011 Location: CT iTrader: (0)	BMW Fault Code 4804 - Reducing Agent no reducing agent pressure build-up possible Has anyone had and fixed this code before? I'm not sure if the problem is a part covered by the emissions warranty. I'm at 99,xxx. Thanks, Attached Images
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03-27-2017, 09:10 AM	#2
135i_vs_ Captain 75 Rep 697 Posts Drives: M5, 135i, 335d, F10 550xi Join Date: Sep 2011 Location: CT iTrader: (0)	From reading a post from another forum, it might be the supply module? Is this part difficult to change? I never even took a look near the active tank area. http://www.realoem.com/bmw/enUS/show...28#16197244137
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12-07-2021, 07:48 PM	#3
kpm Enlisted Member 6 Rep 41 Posts Drives: 2009 E90 335d Monaco Blue Join Date: Mar 2014 Location: GTA, Ontario iTrader: (0) Garage List 1985 325e BMW [0.00] 2009 328i [0.00] 1991 BMW 318is [0.00] 2009 BMW 335d [0.00]	Original owner of stock 2009 335D with 222k kms(138k miles) Outside of recall items, no previous issues since new with emissions system. Having lost faith in my local dealership(useless beyond routine maintenance) and that is being kind, I began to self service in 2020. With COVID 19 et all, having retired and my wife working from home, my D lacked exercise and DEF was getting stale. Early this Fall: "No Start 1600 kms" light,Code 474C Exhaust Fluid warning as well as Code 4804 Pressure control SCR, overpressure fault Refilled only the passive tank with DEF" with hope to using up the stale fluid in the active tank. No start" light cleared after a few days and trips Removed the DEF metering valve and though dry with no visible crystal buildup like othes seen on this forum, I rinsed with distilled water replaced and cleared errors. Error code 4804 has never returned.
	Appreciate 0 Quote