U1200 81 code?

[Stuart W]

I have a U 1200 81 code on diagbox for a c4 grand picasso blue hdi.It relates to the dreaded adblue pump.About 6 months ago I had adblue pump issues showing low pressure and stripped the unit down inserted a pressure gauge and measured the pumps max pressure at well over 8 bar and when the pressure limit sensor was back in it was 6 bar so all as it should be.Everything else tested ok so it went back in and worked fine for several thousand miles till now.I suspect this is more canbus wiring issues again since this car had a previous long running issue which nobody could fix relating to abs /ecu communication.I finally found an intermittent canbus issue and that problem has never returned.
Anyway can anyone confirm my suspicion that U1200 81 is a canbus to adblue pump communication problem ?

[GiveMeABreak]

What's the VIN for the affected vehicle?

[Stuart W]

VF7**************[VIN obfuscated, can be read by forum staff]

[GiveMeABreak]

Not getting this code at all for this vehicle.

Are you 100% you have it correct U1200 is not shown in the list of faults....

[Stuart W]

Yes, it comes up in the brown bar from the edc17c60 ecu and says "ownership not referenced."
Also displays the denox codes P20F6 and P20E8 , the usual denox codes.Yet if I clear all codes it will run again for a random time.

[Paul-R]

Stuart, what version of Diagbox are you running?

[GiveMeABreak]

Strange, although I recognise these other codes, both are not being returned for this vehicle.... (1.6 HDi 120 particle emission filter (DV6FC)

But P20F6 is a detection of a leak in the DeNOx system and P20E8 Pressure of the urea fluid: Urea fluid pressure too low.

So resetting it isn't going to help if it's leaking and causing a pressure loss Stuart.

Check the urea injector for signs of crystallisation there or anywhere back from the tank along the supply pipes. It's not always the tank / pump that are the issues.

[Stuart W]

Thanks Marc, I have cleared all faults but the ecu fault remains u1200 81 , supplier fault code in the brown heading and hitting the + for details gives the ownership not recognised, value not recognised message.
Diagbox is v07.66
Turning ignition on , I can hear the pump run up to pressure and stop after a few seconds as normal but if the engine is started, the pump sounds as if it is running at a very low level permanently.Turning off the engine there is no sound of the reverse pumping to relieve the pressure.
Is it likely that the initial pressurisation is automatically done when power is present at the pump, but the urea cintrol messages from the ecu are not being received or are corrupted? This makes me suspect the canbus again.
Is there an intermediate connector to thecpump that I could check the canbus on without taking the tank out?

[RichardW]

The pump at key on is the LP fuel pump. Adblue pump only comes on after a few minutes when the car has warmed up - with the radio off, I can hear it in our car if idling. Adblue pump should run for a few seconds after engine off to clear the adblue from the system.

[GiveMeABreak]

I also note your vehicle's build date is August 2015 and your Diagbox software was released in March 2015, so it is possible it is a little early and me be the cause of some detection issues. Of course, the risk of updating later may limit some ECU telecoding functions, but again this is a 'may' as it started to move to online telecoding.

[Stuart W]

Thaks guys , it looks like adblue tank out again! Since the return of this adblue error I have not heard the pump running in reverse after ignition off.It always used to.I guess thats because it has not been running up to pressure as it should when the engine was on.Annoyingly I feel amost certain that when I dismantle the tank again that the pump will test ok again on pressure when powered up in standalone mode off the car.I will update you when I get any news.

[CitroJim]

Stuart, I'd be most interested to learn how you initially overhauled your Adblue tank as I've been pondering just how repairable those and the associated injector are.

Conventional wisdom seems to suggest they'e a sealed unit and not repairable but from reading between the lines of what you've previously written, maybe not.

It's always been my plan that if mine fails I'll be looking into trying to fix it...

[GiveMeABreak]

Don't forget to check the supply pipes from the tank to the injector though. Leaks can occur here.

[Stuart W]

Hi Jim, sorry for the delay in replying but thr adblue issue has had to take a second place since the drivers door ehandle ceased to operate- I found the cable outer sleeve anchoring point was a very flimsy plastic clip which had snapped off.This meant removal of the door panel and handle mech to gain access.I have put the sleeve into its slot and anchored it with a cable tie which is far stronger than the original open plastic clip.Now it serms the cooling system is leaking somewhere....
I will eventually get to the adblue again.Last time I removed the adblue tank and opened the cover to access the electronics.I bought a 0 to 10 bar pressure guage and a tee piece, some pipe and the adblue clip on connectors. With this I was able to insert it between the tank and the injector.I applied 12v power directly to the pump and found it capable of over 8 bar with no problem.Then I connected the pressure sensor in and found it operated around 6 bar.I removed the injector and connected it to the pump on the bench.If you dab the injector terminals with a battery it does open and spray the fluid out.The pressure reservoir and the solenoid valve which store the pressure also seemed ok.All plugs seemed clean and well seated so I re assembled the unit (August)and it ran perfectly till now. I will have to repeat the fault finding again now.

[CitroJim]

Thanks Stuart That's absolute solid gold information on the Adblue system - it means there's always a good chance of a fix when they play up. Keen to learn of your second foray into this area.

Sorry to hear of all your grief with the door handle. What a 'mare

These cars do keep us busy don't they