DTC #P20E8

[Gero-75]

Hello, I've recently had a problem with code P20E8, low pressure on the reducer. The problem appeared while traveling with the SERVICE light on without the urea light on and without receiving any prior notifications about the remaining kilometers of mileage. With the SERVICE light on, I traveled about 350 km. The next time I set off on a road, after 7-8 km, the engine problem light also came on and an accompanying message about engine damage and that I should contact a service center. I connected to OBD with ELM327 and that's how I saw the error number. I cleared the error and continued my trip. After 7-8 km, the SERVICE light came on again, but I continued the trip and traveled another 150 km. Since I have no indication of the urea level, I decided that maybe the tank was empty and that's why this low-pressure error came out and I poured 10 liters of AdBlue, which filled the tank to the top. Therefore, I had about 7 liters. urea. I checked the price of a new tank, and it is 2300 lv. I have a few "dumb" questions about the problem, and I would be very grateful if someone could answer me.
1. Why does pressing the Check button on the left of the steering wheel after informing me that the tire pressure is OK show me the remaining kilometers to the next service (in this case 19800 km) and then it says No Fault as the error has not been cleared?
2. The auto parts store where I asked about the price of a new tank with a pump told me that I also have EOLYS. The car's manual only mentions AdBlue, nothing about EOLYS. I also asked the artificial intelligence, and it answered me:
2015 Citroen C5 Blue HDI models that are equipped with an AdBlue system do not use EOLYS fluid. AdBlue and EOLYS serve different purposes: AdBlue is used in the Selective Catalytic Reduction (SCR) system to reduce nitrogen oxide emissions, while EOLYS is used in the Diesel Particulate Filter (DPF) system to help burn soot.
So, if your Citroen C5 Blue HDI has an AdBlue system, it will not have an EOLYS system. If you have any more questions about your car or anything else, don't hesitate to ask!

So, do I have EOLYS or not?
3. If I remove the tank from the car, will I be able to start and drive temporarily without risking any serious damage to the engine?
If it helps, here is the VIN VF7**************[VIN obfuscated, can be read by forum staff]

[Paul-R]

So, if your Citroen C5 Blue HDI has an AdBlue system, it will not have an EOLYS system. If you have any more questions about your car or anything else, don't hesitate to ask!

This is absolutely NOT correct. As you correctly said they are two different systems. In fact if you have Adblue then you almost certainly have Eolys as well. (Latest model DV5 engines do without Eolys and rely upon natural regeneration only).

[GiveMeABreak]

I have a few "dumb" questions about the problem, and I would be very grateful if someone could answer me.
1. Why does pressing the Check button on the left of the steering wheel after informing me that the tire pressure is OK show me the remaining kilometers to the next service (in this case 19800 km) and then it says No Fault as the error has not been cleared?
2. The auto parts store where I asked about the price of a new tank with a pump told me that I also have EOLYS. The car's manual only mentions AdBlue, nothing about EOLYS. I also asked the artificial intelligence, and it answered me:
2015 Citroen C5 Blue HDI models that are equipped with an AdBlue system do not use EOLYS fluid. AdBlue and EOLYS serve different purposes: AdBlue is used in the Selective Catalytic Reduction (SCR) system to reduce nitrogen oxide emissions, while EOLYS is used in the Diesel Particulate Filter (DPF) system to help burn soot.
So, if your Citroen C5 Blue HDI has an AdBlue system, it will not have an EOLYS system. If you have any more questions about your car or anything else, don't hesitate to ask!

So, do I have EOLYS or not?
3. If I remove the tank from the car, will I be able to start and drive temporarily without risking any serious damage to the engine?
If it helps, here is the VIN VF7**************[VIN obfuscated, can be read by forum staff]

1) That is for the range remaining based on the quantity of Adblue in the system. The reading will ONLY start to fall when you have reached the first minimum warning level and only then will it start to countdown. So expect to see it remain at the same level until you reach the minimum. This button has nothing to do with resetting anything.

2) The AI answer is both incorrect and useless - just shows why you can never trust them as all they do is scrape the web for info - and as we all know the internet is full of rubbish: Rubbish in = Rubbish out!

All modern PSA diesels have a particle filter system. Most have Eolys for assisted regeneration except some later 1.5 HDi engines like mine, which has a particle filter but not additive, so relies on passive regeneration. Your vehicle does have an Eolys tank.

Your car manual does not include info about the DPF Eolys system as it is NOT considered to be a user-serviceable operation. It is only designed to be topped up once or twice in the vehicle's lifetime and this is usually done by the dealership at one of the scheduled services or checks at a certain mileage - because it needs proper diagnostic tools to reset the additive counter and is not easily accessible to fill.

Remember:
The DPF (Diesel Particulate Filter) (with or without an Eolys assisted regeneration system) traps the particulate matter.
The SCR (Selective Catalytic Reduction) system uses UREA which is injected into the Catalytic converter to convert the NOx gasses into Nitrogen and Water.

They are 2 different system to do different jobs. Your vehicle has both fitted.

3) You need to have it properly diagnosed first as it may be a faulty sensor or a blockage in the system - don't go replacing parts without knowing the cause of the fault.

However for your C5 X7 with the DW10FC engine, there is a specific technical bulletin that does refer to a replacement Urea Reservoir being required IF:

Lighting of the urea warning lamp and displaying of the message "Emission Control Fault: starting prohibited in xxx kms / miles" on the multifunction screen: if fault code p20e8 is present

So if you are not getting the specific message quoted above along with the P20E8 fault code, it may be another issue.