FIXED - P20E8 on a Grand C4 Picasso MK2 2.0l BlueHDI

[florian-northcoast]

Hi,

In 2018 my wife bought a Citroen Grand C4 Picasso MK2 2.0L 150ps Blue. Approx. 7 years ago (2019-2020) we got our first urea tank error and the local citroen dealer replaced the tank for more than 1000€.

Two weeks ago, P20E8 comes again. The car has driven 189.000km already and is now counting to 0 until it wont start again.

Seven days ago i drained the thole tank, put in AdBlue de-crystilisation fluid (25% more than the recommend mixture) and 10 Litres of fresh Urea because my assumption is, that i filled low-quality ad-blue from a discounter which now has been crystalized in the pump or the pressure sensor.

We drove the car several times and today 30km on the highway. As my wife was driving i red out the DeNox Values

So, the 4 Bar Value shows that there maybe is no pressure on the Nox Injector. Possible the reason for P20E8.

But i worry about the "Distance Remaining before filling the urea reservior" -> "Value invalid"

I have filled up 10 litres.

Could it be, that the pump isn't working because it doesnt know if there is any adblue left ?

Bes regards from Germany ( and sorry for my bad english)

Florian

[RichardW]

You need to reset the fenox system before it will try and work again. But it says it's not pressurising because the tank is empty - combined with the level invalid, I suspect the level sensor in the tank is broken....

[florian-northcoast]

Hi Richard,

thank you for your reply. I could reset the fault with diagbox 7.64 but after 10km or so the UREA warning came back. In the diagbox the Values for the remaining urea are still invalid.
So i removed the urea tank from the car and opened the chamber with the pump and the pcb. I studied https://www.elektroda.com/rtvforum/topic3827598-30.html noted down the Values the Level Sensor and the thermal sensors should have.

Heating is OK with 1,26 Ohm
The sensor on the heating plate (yellow wires) shows me 0.4213kOhm, which is a lot smaller the then 11kOhm it should have.
The urea sensor with the blue wires shows 4.36kOhm (@10°C) which is IMHO in acceptable distance to the 3.3kOhm (@25°C)

The Level Sensor wires should have something approx 800-900Ohm between the wires. Here i get 5MOhm. But, when i supply the Sensor with 5 Volts and messure the white Line my multimeter shows 4,4V in a stable horizontal position of the tank and 1,5V if i tip over the tank. So. I think this sensor works somehow.

so i don't know which next step i will go. I found a dealer in Germay who sell refurbished tanks with warranty (https://www.turbo-tec.eu/en/adblue-tank ... -warranty/).

If the sensor in the heating plate is the problem i could only solve this problem by adding some resistors inline. But then i must take care in the next winter season

Maybe someone of you also measured the wires of the sensors and could confirm that my sensors are defective.

Best regards

Florian

[florian-northcoast]

Short addendum:

https://www.elektroda.com/rtvforum/topi ... 8-210.html said:

Unplug the yellow plug and measure the resistance and you will know if it is faulty, usually when faulty it has a low resistance around 300 ohms.

So i bought https://www.amazon.de/dp/B07Y1THCF6?ref ... asin_title 10k Thermistor incl. wiring to replace the defect sensor.

stay tuned.....

[Trickiedickie]

This is a very interesting thread. Please keep us informed as to how it goes.

Do check the Adblue Injector because if it fails or is blocked it will likely produce the P20E8 error code. This will of course stop the pump from operating so will show the 4 bar (no pressure) reading.

[florian-northcoast]

Thank you for this Info. I'll have a Look at that

[florian-northcoast]

I think i'll surrender. I replaced the faulty thermo sensor with the 10k Sensor. But the values in Diagbox are still invalid.

Now i have even more Faults on my systems. ECU CAN Failures. And further more. Sometimes the Display shows "Failure in electric wiring". The problem is, that i doesnt have the time to go deeper in the rabbit hole. I will order a new urea tank and ship the old one back due deposit.

I testet also the pump it self via diagbox with a transparanet tube. But i only heard four minutes of clicking noises.

Thank you all for your help.

One of the new Errors is P0215 77

may be all of this error will dissappear if the car is driving again.

[florian-northcoast]

In Short: Urea Tank is working again, no ECU / BSI Errors

What was happen
Days ago i decided to do not try on this tank anymore and let the shop replace it with a new one (1500€). As i said i need this car working in the next weeks.
So i give it one last chance. I supply the pump with 12V to see if its working -> Works. I dissambled the solenid valve a give him 6V -> Working. In the same moment lquid Adlbue rans out of the valve housing. So don't see any kind of crystallization. Then i remove the connector from the PCB and connect them again. (Maybe a connection issue cause all the trouble)
After that i put everything back together. Still with the replaced 10kOhm thermosensor.

At the car i did the BSI procedure while mount the adblue tank back to the chassis. (https://www.frenchcarforum.co.uk/forum/ ... 51&t=61997) ( I connected the tank after disconnect the plus from the battery). I used electronic contact spray for the electrical joints (www.kunzmann.de/shop/de-de/p/sonax-elek ... -35438.htm)

After BSI Reset procedure (turn on engine was one of the last steps) i connected DiagBox and check for fault on the BSI subsystem. There were plenty of them. I cleared all of them. Nothing permanent oder temporay left.

In the next step i did "Reinitialisation of the DENOX System Fault"

After that i cleare the Fault for the whole ECU Section. No faults left after clearing.

Now the correct temperature value is shown. There current level is still invalid

Great! My smile getting bigger and bigger -> RoadTrip

With the laptop on the other seat and the DENOX Info 1 Page open, i drove the highway for several kilometers.

After some time the pump kicks in and then et voila

So. I think the main reason for defective tank was this termal sensor. Maybe this BSI Reset procedure or the cleaning of the contacs was the last missing piece in this puzzle.

Thank you all for your support and the tips.

Have a great weekend,

Florian

[RichardW]

Well done!