2017 Grand Picasso P20e8 error code - how to diagnose

[Colincliff]

Hi, I have a 2017 Grand Picasso which has started giving the P20E8 00 low pressure error and the dreaded 700mile countdown.

I have Diagbox and was wondering the best way to use it to diagnose using the Diagbox system to try to narrow down the source of the issue. I can hear the Adblue pump working when ignition is turned on and when I do an actuator test in Diagbox, but I am not an expert in the software and would love anyone who could advise on what menu items to try or parameters to check to work out if a new tank is the only option.

[Paul-R]

You need to run a global test with your Diagbox to see what error codes (DTCs) are reported. Then clear as many of the DTCs as you can and see what won't clear. Then run the car a for a short time and see what errors come back.

You can reset the 700 mile countdown by using Diagbox to reinitialise the NOx system.

[RichardW]

That's not the ad blue pump you can hear at key on - it's a low pressure diesel pump in the tank. You need to reset the DeNox system, clear the fault codes, and then run the engine and watch the denox live data as the engine warms up to see what it is doing. You should initially see 4 bar pressure (the minimum it can read - if less there is a fault in the pressure sensor or circuit), and status of standby. It should then move to pressurising, the AdBlue pump should run (you might be able to hear it) and the pressure should rise to 6 bar, then it says waiting or something, before it moves onto injecting. At this point you should see the NOX level fall, and the pressure will drop to around 5.5 bar. Where and how it falls down should give an indication as to which part is at fault.

[Colincliff]

That is really helpful, thank you. I've reset the DeNox system and deleted the codes in Diagbox. The global test is giving me the error codes P20EE and P20E8 both of which suggest a blockage somewhere around the pipes or injector from what I understand.

@RichardW - I'll give that a go tomorrow and see if I can see at what point the process fails. I added a couple bottles of Wynns Crystal Clean & Protect when the error first appeared a few days ago so hoping that this is just some crystallisation that may be able to sorted. I assume if everything follows the process you listed and the NOX values fall with no errors then the system is working fine?

I also found this really helpful post that explains the process that I should see if the system is running ok - viewtopic.php?p=726806#p726806

[RichardW]

Unlikely to be a blockage as that is a low pressure code. So either the pump, the sensor, the electronics, the cabling, or injector stuck open / leaking. The P20EE code is just generic 'it's not working'

[Colincliff]

I've just done a run for about 10 miles and annoyingly no errors and everything seems to be registering correctly looking at the live data. Pressure was remain around 6 bar or very slightly under during that time.

However, I then did an DeNox bleed test in Diagbox and I'm getting a fail saying "bleed to rapid" - perhaps pointing to a leaking injector?