Good morning, this Fiat Doblò 1300 Multijet sometimes switches off on the run or some mornings it has great difficulty starting up. Unfortunately we are never able to catch it in the act when it does this problem. The customer reported that since the service with the replacement of the diesel filter (his was very clogged up with dirt) the van has been giving this problem.
On diagnosis, the dtc is P0089 (high-pressure fuel pump/high-pressure pipe functional disturbance).
From what we have tried to understand from the customer, when the fault occurs, the vehicle runs out of diesel in the system...so it doesn't turn off suddenly, but slowly. We have changed the in-tank pump (Bosch) twice, because the first one also had a problem...2 diesel filters, cleaned the tank (it wasn't dirty), fuel pump relay, had the pump overhauled (worn in the pumping unit) and put on a new DRV because his old one had small leaks of diesel from the electrical part, blown the delivery and return pipes. We thought we had solved it, but the problem remains with the same dtc. Looking at the wiring diagram we ruled out the inertia switch (but the fault did it again) and bypassed the wire going in and out of the bodycomputer (it makes a bridge inside it, looking at the wiring diagram), but the fault still does it, because after delivering the vehicle the customer called us back to say that it had broken down (it had been running in the workshop for several hours). When we arrived at the site we found that the diesel delivery system was empty (tank with half the fuel). I was thinking of a problem with the diesel filter holder, but instead nothing. It occurs to me that on certain occasions there is no more power supply to the pump in the tank and so the vehicle shuts down...Then by dint of insistence it starts up again. I have already tapped the wires leading to the in-tank pump, all OK. I tried to recreate the fault by disconnecting the sensors at the rail, but the fault is not the same as the dtc. As a last try I went to the wrecker to get a fuse junction box located in the engine compartment.....As a last resort I thought it's not the engine ecu....But it seems strange. Thanks for the help if anyone has experienced a fault like this.