[135i_vs_]

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_]

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]

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.