Good morning everyone,

It's been a while since I last posted on here. But once again I require the help of the experts. For whatever reason I need to drain my adblue tank. I have looked on line, tried putting a line down the filler neck but it just doesn't feel right. There seems to be something stopping the pipe going down and there are what I can only describe as ridges. Does anybody know if there is a drain plug or do I just persevere with the filler neck and syphon it out.

Thanks in advance to any and all who can help

Simon 

Sorry guys should have said car is 2015 A4 2.0tdi 163 ultra.

Edited May 8, 20251 yr by Confused

I guess what you are feeling is crystallised Adblue, which is a common problem in such systems, and presumably why you want to drain the tank.

In theory Adblue, which is principally urea, is very soluble in water so it should be possible to flush the crystals out with a stream of cold water. However I have never had anything to do with Adblue in my car so I do not know how practical the idea would be.

19 minutes ago, cliffcoggin said:

I guess what you are feeling is crystallised Adblue, which is a common problem in such systems, and presumably why you want to drain the tank.

In theory Adblue, which is principally urea, is very soluble in water so it should be possible to flush the crystals out with a stream of cold water. However I have never had anything to do with Adblue in my car so I do not know how practical the idea would be.

 

Thanks for the reply, I'll give it a go if can't find a drain somewhere 

If cliffs idea doesn't work you can get the adblue system mapped out. 

1 hour ago, Steve Q said:

If cliffs idea doesn't work you can get the adblue system mapped out. 

Yeah done this but the guy recommended remove the adblue. You reckon this is unnecessary then? I don't know just going off what he said. To be fair he also said it won't do anything as the system is no longer working but as a precaution.

For legality it's better to have the adblue working so try cliffs way first if possible. As getting it mapped out is technically illegal 

On 5/11/2025 at 5:28 PM, Steve Q said:

For legality it's better to have the adblue working so try cliffs way first if possible. As getting it mapped out is technically illegal 

Yeah know it's illegal but it was either that,or, a god knows how much bill replacing parts that actually where working as the garage I took it to for diagnostics could only narrow it down to either the adblue pump (£800+) or an injector (£600+) and they couldn't even say for deffo it was either one. To be fair I did speak to somebody at Audi and he said he'd never know a pump to fail and was more loto be one of the lines. But needed the car for work, so....went with the map.

Car feels great though. Picks up better, smoother the all the gears. Drives like it never has since we had it. It's 10yrs old this year and feels like new. Do like Audi engines just !Removed! expensive to keep on the road.

I have to make you aware of the legalities of it as a staff member. I fully understand why you went down the remap route. 

This is the thing, regardless of how old audits become the servicing is always expensive.