What a result Tom309! i've just been outside and checked mine, annoyingly i went over all the fuses with a multimeter and buzzed them all out but F4 was also blown! so changed that but still have the urea fault but for some reason with the urea injector unplugged i have 12v+ to both cables (purple and white) going to the urea injector and the car is still reading around 3000 degrees C
Tom309 wrote: 27 Feb 2024, 15:57
I've just gome through all the fuses in the engine bay fusebox and found F4 (5A) was blown. I could not find any reference to this fuse on the web, but my Adblue injector now works!
So looks like the fault with the C4/Picasso is also a blown fuse. Probably a different fuse number and rating compared with my 2015 308.
Note that my fuse blew due to a short-circuit injector, so if your's has blown, it will be worth checking why.
When I put the new fuse in, my fault did not automatically go off. So I had to reset it manually. Do you still have the fault on the fume heater?
-As long as the rain holds off, I'll measure the voltages on my injector connector tomorrow morning.
Yeah i had attempted resetting the codes, the crankcase fume heater has now gone which is a nice result. i was wondering if doing a resetting/reinitialising of the denox system may help. I'll have a play after work
I've measured the voltage on my 308 when the connector is disconnected from the Adblue injector (Ignition on, engine not running)
Pin 1 to chassis earth: 12V
Pin 2 to chassis earth: 3.4V
Pin 1 to Pin 2: 8.7V
I couln't see the wire colours, but I've attached a picture of the connector with my "test" wire. Pin1 is black & Pin2 is red
Thank you for measuring it, I have have 12v+ on one pin and 12v+ on the other and about 1.8v pin to pin.
But if I introduce a - to the white cable the urea injector works….
Also looking into the denox parameters it’s says my tank is only 1.1L
I’m starting to think either I have an ecu fault or someone has been playing around with this system….
If you mean Diagbox 7.57, then no, it is likely too old for the vehicle. DV V9.** is usually required for vehicles 2016 onwards as the ECU and or the ECU software can change and older versions of DB won't have the software to communicate or read them properly.
But regardless, there are 2 separate systems on the vehicle: An SCR system (Selective Catalytic Reduction) to treat NOx (Adblue) and a DPF to treat the particulate matter.
So you will have data relating to both systems, it's not one or the other it is both, which is why you are showing data for both.
Please note, I'm no longer active on the Forum, so won't respond to messages.
yes sorry i meant V7.57
Right that makes sense.
I dont suppose you have any suggestions on where to get the latest diagbox from or which version is the best to use?
Right……….. so I’ve finally managed to get diagnosed 9.129 running and plug the car in….. good news it that diagbox now doesn’t think my car coolant temperature is 3000 degrees C but! I do not have communications with the urea ecu, and have some extra faults.
U0118 87
P1435 00
U1218 81
P2047 00
I’ve cleared the faults and only the P2047 has come back but I have a feeling I’m taking the urea tank out
The U1218 81 code is likely to be the issue. Unfortunately this is a communication / data network fault and the same code can apply to multiple systems (video camera and safety systems / Engine ECU Systems etc.), so I can't give you specifics, but this will affect comms on the network and where the engine ECU is concerned, this can mean it is not getting the info it needs.
You may have a fault in the wiring from the rear where both the Eolys additive tank and the UREA tank are located. I'm trying to locate a post I did on this some time ago, but I just can't locate it for now..
Please note, I'm no longer active on the Forum, so won't respond to messages.
"Urea ECU - communication error":
I suspect that you don't have a separate Urea ECU. At least I don't, the urea tank comms is done through the engine mangement ecu instead.
In my case the Urea ECU is shown as "not present", but I have other ECUs that are not fitted that show "communication error".
[I suspect that the version of "communication error"/"not fitted" message that is displayed depends on the version of Diabox (I'm on 9.68)]
Plus the usual error for no comms to the urea tank is the error U029E "Fault in the communication with the deNox system -no communication"
If you look at the engine management ecu, parameter measurement it will show Denox1 & Denox2. If they have valid data, then I would say that you don't have a separate urea ecu.
On the other comms errors:
I quite frequently get comms error (when I look using Diabox) and suspect that CANbus is not very rohbust on these PSA cars.
If you can reset the error, I would suggest ignoring it as a "phantom fault" especially if you have disconnected the battery during the fault finding [Make sure you follow the disconnect procedure!!]
Adblue Injector:
First, if you haven't already tried it, it may be worth telling the engine ecu that it has a replacement injector.
Was the 12v+/12+/1.8v measurement with the injector dis-connected (and was it 12v/10v/1.8v)?
On the "if I introduce a - to the white cable the urea injector works…." was that this with the injector wiring plugged-in and the ignition on?
As engine ecu monitors the switched side of the injector I would have expected the error to change from "injector open circuit" to "injector short to earth". Did you see this?
I would suggest the following to see if the monitor still works:
Remove F4 and the injector electrical plug. Measure the voltage to chassis earth to each of the connector pins. I would expect pin 1 to be 0V and pin 2 (which I think is the white wire) to be about 2 to 3V. With the fuse removed, I would expect in to be below 5V.
If pin 2 is below 5V, connect it to chassis earth by a test wire, turn on the ignition and check that Diagbox now shows "short-to-earth" in place of open-circuit (I have done this test on my car).
Thank you guys for the usefull information, im going to remeasure everything and get some better information tomorrow or saturday when the weather becomes better.
I did connect diagbox into the car tonight to have look through diagbox as it was raining, i checked the parameters to the denox system which is showing miles till refill (5000 miles 6.1L) but what i did notice is one nox sensor read 0 ppm and the other 20 ppm which didnt change as i revved the car - as this system is new to me and i know nothing about this but i would expect some movemet?
also the pump was at 4 bar and didnt move, i thought it should be around 6 bar?
Diagbox let me do a regen which then came up with a nox sensor fault, i tried telling the car it had a new urea injector and new nox sensor which failed.
Im now wondering if i have a can issue but when i get some better weather i will jack the car up and check all the connections underneath to the urea tank and nox sensor and do the test Tom has suggested for the urea injector
In the mean time im trying to source a workshop manual and wiring diagram - does anyone have any suggestions?
but for some reason with the urea injector unplugged i have 12v+ to both cables (purple and white) going to the urea injector and the car is still reading around 3000 degrees C 
