Just bought an original sensor for C4 Grand Picasso. There is an option to order a sample, even the shipping on the first order is free. About 22 EUR with tax. Occasionally an error appears, so I ordered it as a precaution, so that I have it close by if I need it! So far only an error in the FAP application, it has not yet popped up on the dashboard.
Before spending serious cash, I'd recommend using some Wynns, we had the the usual error codes but some fresh Adblue and a bottle of said Wynns soon seems to have fixed it. I've put it on subscription from Amazon. Of course I had to clear the faults but that was easy too using the OBD diagnostic tool that I have.
Of course we have the dreaded combination of a new camshaft belt being needed and replacement of the dpf filter etc to look forward to in the next 12 months, so it may be prudent to be looking for a petrol car instead.
I have C4 GP 1.6 Hdi-Blue 2015. Topped up tank at Morrisons at 46000 after warning light. All okay. Had Urea and red engine fault message at 58800 miles. Put 8 litres in to fill the tank. Warnings stayed on then went off then returned. Read the horror stories but then discovered Wynns adblue additive. Put one dose of 125ml in. After about 120 miles all warnings have cleared.
wellsedd wrote: 15 Aug 2025, 11:39
I have C4 GP 1.6 Hdi-Blue 2015. Topped up tank at Morrisons at 46000 after warning light. All okay. Had Urea and red engine fault message at 58800 miles. Put 8 litres in to fill the tank. Warnings stayed on then went off then returned. Read the horror stories but then discovered Wynns adblue additive. Put one dose of 125ml in. After about 120 miles all warnings have cleared.
That's a result It does indeed seem to do what it says on the tin...
Hello,
I had your problem. I bought a test piece of the sensor and replaced it.
Now everything is fine.
Thanks for the instructions. My car is a 508 2.0BlueHDI 180hp
Hi all,
I have this Euro6 Citroen Jumper (a.k.a. Relay in your country), I bought it modified as a campervan but also modified by previous owner on both emissions devices - Adblue and DPF. Currently I'm in progress with the DPF cleaning after software restoration (original firmware is running on ECU now) - I have details in another thread - but I'm also with an eye on the restored Adblue system, which throws error P20E8. Until now there isn't a start countdown message- yet.
On the DiagBox both heater tests are failing (pipe heating and tank heating) and I hear no pump noise. My feeling is that I have a defective tank rather than a pressure sensor, but I haven't take the tank down to measure the heating elements and the NTC (the procedures are on the Elektroda forum). Does anybody has these problems with the heaters - or these tests are both failing from other causes?
Those who don't know history are destined to repeat it!
Hi, thanks to all for the provided information.
Currently, the sensor on Alibaba is listed with the options 0-5 bar, 0-8 bar, 0-12 bar (1200 kPa). Which one should I choose? 0-8 bar? Should I ask the seller for different range?
perfidus wrote: 15 Oct 2025, 21:04
Hi all,
I have this Euro6 Citroen Jumper (a.k.a. Relay in your country), I bought it modified as a campervan but also modified by previous owner on both emissions devices - Adblue and DPF. Currently I'm in progress with the DPF cleaning after software restoration (original firmware is running on ECU now) - I have details in another thread - but I'm also with an eye on the restored Adblue system, which throws error P20E8. Until now there isn't a start countdown message- yet.
On the DiagBox both heater tests are failing (pipe heating and tank heating) and I hear no pump noise. My feeling is that I have a defective tank rather than a pressure sensor, but I haven't take the tank down to measure the heating elements and the NTC (the procedures are on the Elektroda forum). Does anybody has these problems with the heaters - or these tests are both failing from other causes?
yes fixed mine after after noticing there was the default (0 °C) showing in the denox2 section for "Temperature of the urea fluid in the urea reservoir", diagbox diagnostics. Easy 10k ohm resistor soldered in to replace tank's thermistor. All is shown earlier in the post and over at Elektroda forum. Mines good 5k miles later
So I wanted to update on how my issue has stood after a period of time. As mentioned I got an initial fix flushing the pressure sensor with hot water. After an uneventful 4 days the low pressure fault returned and I immediately thought the fix had failed. I sourced all the parts to do an external pressure sensor setup and went about modifying the pump assembly. However when it was all set up and mounted back on the car I still exhibited problems. Occasionally it would work but more often would fault out. I stripped the adblue tank back out again and began a detailed investigation. Turns out the original sensor was still operating (this being checked by using bench power supplies and manually operating pump and solenoid). I eventually worked out that pump was struggling drawing the adblue out of the tank, my guess being the filter gauze had become blocked with crystallised adblue. Remembering how a hot water flush had cleared the sensor initially, I decided to empty the tank completely and then back flushed the system with two buckets of hot water by running the pump in reverse (again using bench power supply). I ran the pump in about 2 minute cycles as I didn’t want to over heat the motor windings or solenoid coil.
Now 6 months on and not an issue since, and all still running on the original parts (I stripped out the bypass transducer if had fitted).
Might be worth a try for someone experiencing issues.
earlsgate wrote: 14 Nov 2025, 17:32
yes fixed mine after after noticing there was the default (0 °C) showing in the denox2 section for "Temperature of the urea fluid in the urea reservoir", diagbox diagnostics.
After more hundreds Km of driving with the van I have found an interesting information. I noticed from the start that my reading of temperature of the urea was consistent with the ambient temperature so my trouble was slightly different from your case.
Now after a long trip with a few stops and starts along the way, the P20E8 error is not anymore marked as permanent, I have no engine malfunction light, and a scan with my mobile phone app (EOBD Facile) turns up with a surprise: a reading of 6 bar for urea pressure and the status of the deNOx system changed from "urea pump stopped/empty" to "pump stopped/with urea" - this tells me that for this trip the pump started working and maybe the only problem that I might have is the crystallisation inside the tank/urea filter pick-up due to long time spent with no Adblue inside the pump, the accumulator or the pipes. I will give a try to the hot water treatment (thanks Martin for your update).
Those who don't know history are destined to repeat it!
Hi everyone! I have a 2015 C4 Grand Picasso and couple of days ago I got the Emissions control faul and engine fault errors. For some background, the car was standing unused for about 2 weeks in 2-3 degrees celsius. Then everything was fine during 5-6 trips and then the errors showed up when the outside temp was -12C - not sure if this is related. I checked the error codes with Diagbox and for P20E8 00 error code Pressure of the urea fluid with the following details:
cause: local
status: permanent
characterisation of the fault: Urea fluid pressure too low (4.000 bars)
temperature of the urea fluid in the urea reservoir: 0 celcius - it was -3 outside but if the reading stays at 0, does it mean anything?
Operating status of the deNOx system: Urea gauge-pump module stopped
I read through the whole thread and I would like to ask for your advice. Based on the readings from the Diagbox, is there anything that I can easily test?
1. For example, if I get the car up to temp, clear the codes and keep the car running while listening to the pump sounds, will I be able to check if the pump at least starts? Is there any better way to test this without removing the tank? I do not have the equipment to lift the car up and remove the tank.
2. I am happy to buy one of the anti-crystallisation agents but I guess that if the pump is not starting, this will not change anything? I believe that I have 7-8 liters of AdBlue in the tank. Does it make sense to add the solution if I cannot drain the tank first to flush it? Is there a way to flush it without lifting the car up?
3. It sounds like checking the injector is important. I will try to see if I can get a look at it without lifting the car up. If not I will talk to my closes mechanic about it or look into buying a simple drive on ramp to lift the front (for the injector) or the back (for the tank).
Any other advice before I start looking for a new tank? Thank you!
edit: I just wanted to add that I tried activating several tests in the diagbox related to the deNOx system but every time I would do it, I would get a message stating that I should perform an actuator test first. All of the tests I was trying to run were in the "actuator test" menu. Does anyone know what this is about and how I can perform those tests? I think that there was one that would activate the pressurisation pump.
If you're constantly getting the 0 degC reading there's a good chance the tanks heater thermistor is gone and can be replaced with a 10k ohm resistor. Check through this thread again and there should be details of how to do it
Thank you, I will check that. I also saw that "Urea heated pipe heating power" is always at 0 but same here, I will check it during or after a longer drive.
Could this lead to the error alone or is it more that this error would cause the pump breakdown?
edit: does anyone know if one of those simple drive on ramps would be enough to remove the adblue tank? Or to ask this differently, how high do you think I need to lift the car to remove the tank?
Last edited by qwertyqaz on 18 Jan 2026, 20:49, edited 1 time in total.
It does indeed seem to do what it says on the tin...