Multiplexed Additive Pump Faults

[timjeans]

Hello, I am looking into some DPF related faults on my 2013 Citroen C4 Grand Picasso. There are many! I thought I would start with two faults within the Engine ECU that can be cleared but return when the car is started. They are:
Multiplexed Additive Pump CAN Fault Or Additive Pump Fault
Multiplex Additive Pump, Pump Fault
For some unknown reason my iCarsoft reader is not giving me numbers.
Can somebody tell me how these are set?
Are they only set if there is a canbus comm error with the pump?
The Multiplexed Additive ECU is recording a fault P0EB0 Additive Reservoir Empty Fault. Whereas the Engine ECU says there is 1846 mL left.
Could this set those faults above?
I refilled the tank a little while ago and thought I had reset the necessary parameters but maybe not!
Any help would be appreciated.

[GiveMeABreak]

Best if you pop your VIN ups so I can see which vehicle and system you have. (please post your VIN in full without spaces - it will be automatically masked from public view after submitting your post & will only be visible to staff).

The quantity of additive remaining is not physically measured, just estimated from when last topped up against metered doses for fuel added. If not reset correctly it will flag the warning when it thinks it has reached a low level and based on the mileage remaining until your next service from the maintenance indicator.

We had a recent one of these here IIRC where on checking the wires back from the additive pump there was a break. So may be worth checking.

Once I have your VIN I may be able to get the correct descriptor for the fault.

[timjeans]

Thanks for such a prompt response much appreciated.
The VIN Number is VF7**************[VIN obfuscated, can be read by forum staff]
I put my scope between ground and the signal wire and could see a bitstream.
Doesn't prove that there is comms but there must be data coming from the ECU as the pump module dosn't output data when powered up on the bench.
I am thinking that the pump failts in the engine ECU may be a result of the P0EB0 fault in the Multiplexed Additive ECU.
Thanks again.
Cheers
Tim

[timjeans]

Put the scope on the can bus without the pump connected and the data stream looked very similar.
In both there were gaps.
The ECU is definitely polling the pump but not sure its responding.
It will be interesting to see what the description of the pump faults within the engine ECU say.

[GiveMeABreak]

I'm not getting anything back from Citroen with that fault code - doesn't come up - are you using Diagbox or Lexia?

[timjeans]

Used an icarsoft code reader.

[timjeans]

Maybe I should by a Lexia3 interface and take another look? I presume this will allow me to do all the resets applicable to the DPF and additive pump?

[GiveMeABreak]

Yes, it's a clone interface of what the dealers use.

No guarantee of course, as some older vehicles like this one that use on older engine and EMS don't always have as much info on the faults as later vehicles, so hard to say.

[timjeans]

Thanks for your help I have a think and let you know how I get on.

[Paul-R]

There are good and not so good copies of Lexia/Diagbox. Perhaps wise to post up what you're intending to buy before splashing out.

The forum gains nothing from it but there is a discount available for valid forum members from Easydiagnostics, purveyors of a good version. See here viewtopic.php?t=60113

[MH123456]

If it's anything like the 1.6 HDI in a 2007 Focus then if you don't reset the DPF counter and reinitialise the ECU it will throw a fault for fluid empty when it's calculated on the previous reset even though it's possibly full. Mine did that shortly after I got it, I tried to refill but only put about 200ml in to get it full. Did a full reset and that sorted it. It should only be done when the tank is full. I doubt it is related, but if secondhand then double-check the open/close readings from the filler cap (if it has a magnetic sensor there). These can go bad or fall off - at least in Fords - RIP my poor Focus.

If anyone needs some Eolys fluid, I think I have a full litre in the shed with a part bottle and filling kit, just message me for info.

[timjeans]

Thanks for your input guys. Ill try a version from Easy diagnostics. Mine was a nightmare to install and still unstable! Anyway as the post above all it needed was a reset. For anybody with a similar problem this is the story:
Filled the additive tank a little while ago and got the fault reset by a mobile diagnostics chap. Nor sure exactly what he did. All was well until the faults below appeared - car in limp mode:
BSI ECU
FEB3-Fault diesel additive pump control
Injection/ignition ECU
P1445-Additive adding
P1435-Multiplexed additive pump
P1434-Multiplexed additive pump
Diesel additive adding pump ECU
FEB3-Additive pump fault
FEB0-Additive reservoir empty fault
So the faults seemed to be telling me three things:
1. The additive pump was faulty
The best price for a replacement was £330 so I decided to do more fault finding. P1434/5 says can buss error and pump fault.
I put a picoscope on the bus. The serial decoding showed that with the pump fitted there was data from it and when disconnected the data disappeared.
The pump would operate fine when grounded. (the PIC in the PCB uses a transistor to ground the pump)
Also with the pump connected P1434/5 would re-appear (once cleared) once the engine was started. With it disconnected a fault would appear with just the ignition on. (cant remember which one)
I was reasonably confident that the pump was good.
2. The amount of additive used meant that the DPF had to be replaced.
The differential pressure sensor did not show an excessive pressure drop across the DPF. I did not want to replace it unless I could see that it was blocked.
3. The additive tank was empty
It was nearly full
Based on the above I programmed the car to say that it had a new DPF, Additive Tank and that the tank was full.
The car was then fault free and has been driving fine.
I can imagine when this happens that there is a temptation to spend a lot of money on new bits.
I will have to keep an eye on the DPF. Maybe the engineers time it out for good reason.
The additive tank fault is nonsense. It is simply a solenoid pump, tank and PCB.
As it can be filled it should last the life of the car.
The chap in the parts place said they sell a lot of them!
Thanks for your help with this. A good forum.

[Luscious007]

Please could I get some advice. I am female and I am worried that I am going to be charged a fortune for something similar. I have a DS3 16 plate. Vin no VF7**************[VIN obfuscated, can be read by forum staff]. Current mileage is 55,000.
The garage ran a diagnostic on the car and it came back as U0118 fault. P1435. Can I be given some idea as to :-
a - can this be repaired and if so cost in GBP
b - if it’s a replacement again any idea of cost
c - why has this broke it was only in March 2023 when I had to have the DS3 Adblue system repair.
d - do these cars start to have faults given age and mileage

Thank you for any help and advice.

[GiveMeABreak]

Your VIN is incorrect and 2 short.

My observations....

The codes indicate there is a problem with the multiplexed additive pump or on the communications network that connects it to the BSI (the car's main computer).
But some people just assume that replacing the additive pump is always the solution - it is not. We have seen cases here with the same / similar faults and it is the actual wiring connections between the additive pump and the BSI. In these cases replacing the pump won't help. The wiring has to be checked from the additive tank connections and traced back and inspected. In many cases the connections or wiring were corroded or damaged and this was causing the comms fault on the network. If the BSI can't communicate with the additive pump then it will throw a fault code (s) up.

But see my note at 'c', you may be confusing the Eolys additive system for the DPF, with the Adblue additive system for the Self Catalytic Reduction.

So it needs proper fault finding from the tank connections back to find the fault. If these connections, pins in the connectors and the wiring have been thoroughly checked then go back to the tank (was it a brand new or used one that was fitted) - if it was a second hand tank assembly, it may have already been or become faulty itself.

a - can this be repaired and if so cost in GBP

Yes, but needs a competent garage to properly diagnose the fault cause and repair. Impossible to provide a cost estimate until the cause is ascertained.

b - if it’s a replacement again any idea of cost

See (a) ^

c - why has this broke it was only in March 2023 when I had to have the DS3 Adblue system repair.

The Adblue system is nothing to do with these fault codes. These fault codes are to do with the DPF Eolys additive tank, which is completely separate from the SCR system that uses Adblue to treat diffrernt types of emissions (NOx).

d - do these cars start to have faults given age and mileage

All vehicles will develop faults at some point but in your case it seems it it possible as 'c' that the fault was not correctly dealt with previously, hence the reoccurrence of the issue. You didn't mention if you has the same fault codes previously.