emissions fault : starting impossible

[EtoiledesNeiges]

Citroen Berlingo & Vauxhall Vivaro (same engine)
VANS NOW WITH 'EMISSIONS FAULT : STARTING IMPOSSIBLE'. Anyone who encountered this, remedial actions taken?
Comes after a few 100miles, no warning
both vans started with message 'emissions fault vehicle will not start in x miles' initially
* new injectors ( one even a new engine)
* new adblue injectors
* adblue resets (many)
* sensors, nox
* adblue flushes (suspected adblue had crystalllised)
Dealer & independent at loss to find the underlying issue
Any help welcome as to remedial action

[Paul-R]

What model?
What year is the vehicle?
What engine?
How many miles has it done?

EDIT - I see it is the 1.5 Blue HDi engine.

[GiveMeABreak]

As you have 2 vehicles with the same issue, and different models, I'm inclined to suggest have you had these 'chipped' / remapped? Anything like that can affect the system.

[EtoiledesNeiges]

not remapped, not chipped,
vehicle used at different sites
Adblue bought from forecourts
the vivaro is a 21 plate with 36200 miles (new engine/ new injectors, new adblue injectors, adblue resets x6, nox sensor, adblue flushed & replaced)
the berlingo is a 20 plate with just over 64k miles (timing chain, water pump, resets, adblue injector)
both vehicles are serviced according to manufacturers guidelines
our drivers are asked to keep oil, coolant (and other fluids) topped up regularly (small regular top up) and keep level at 75% full
adblue is treated is topped up way before empty ** this is for all our vans not only those 2 **
it does not help when one of our deler has the same issue and they reset the UREA parameers regularly on their own vans as they cannot get to the bottom of the issue.

[GiveMeABreak]

It may be more use if we had the actual fault codes to see what area the issue is with.

[djadams]

Reading the above, one possibility that springs to mind is that the adblue may be over-full. One of the anti-tamper requirements is that the software needs to be able to detect a spoofed adblue tank level sensor signal (which might be telling the system the adblue level is OK when it's actually empty). The only way the software can tell that someone hasn't messed with it and replaced the level sensor with a resistor or whatever is to see the level moving around as adblue sloshes around when the vehicle drives around corners and so on. If the level in the tank is too high (it's been topped up when it didn't need to be) then the level sensor will be up against it's upper end stop and not moving - which would give a signal plausibility fault. It's possible that telling the drivers to top up the adblue when the vehicle isn't requesting a top up has caused the problem. If that were the case, the fix would probably be draining the adblue tank completely, then refilling it only with the recommended quantity, then resetting faults and taking the car for a short drive so the system can confirm that the level signal is now moving as it should. If no more detailed fault code info is available, draining the tank and comparing the amount that comes out to what the recommended fill volume is might be a relatively quick check.

Source - I used to develop OE diesel engine management systems for a living, before VW ruined it and diesel engines went out of fashion...

[GiveMeABreak]

These do have a overflow outlet, so will expel any over-fill. I did this when topping up one month, but no issues at all and I've done this several times as I like to top mine up fully every 3-4 months. Mine is a later system though and a different tank, so there may of been some changes over the years.

[djadams]

These do have a overflow outlet, so will expel any over-fill. I did this when topping up one month, but no issues at all and I've done this several times as I like to top mine up fully every 3-4 months. Mine is a later system though and a different tank, so there may of been some changes over the years.

Yep - if these vans have an overflow to avoid overfilling, that would definitely negate that potential issue!

[EtoiledesNeiges]

the citroen Berlingo is getting a new adblue tank. I undertand it comes complete with pump etc.
as to the Vauxhall Vivaro it is in the queue for the dealer to look at (again)
There is no warning to fill up the adblue, on either van
We get straight away the adblue emissions fault start impossible message
We managed to drive the berlingo c. 300 miles between incidents, around 200 miles for the vivaro.
Adblue injectors have been replaced,
The adblue was suspected to be substandard, was flushed out and replaced with some 'good' on form the dealer,
but the fault is still happening
it seems the engine can restart straight away at least once when the engine is warm
If we await 30 min, then there is no start