[Warning Light] Limp mode after refuelling

[Tom Wilton]

Hi all, I’ve had an issue with Berlingo (13 plate) for 4 months now. My car went into limp mode back in November. After being scanned it turns out they a new fuel tank was needed and the pressure was low. A new tank was fitted, pressure was tested and was fine so rejuvenated the system. The error codes disappeared and car was back performing great. All was good until I filled up with diesel. After this the car went back into limp mode. After returning the car the same codes appeared on the scanner again. We rejuvenated the car and drove fine again until putting more fuel in. This has gone on for months. I recently had to drive 300 miles to Leeds so filled up with diesel, rejuvenated the system and was fine until having to refuel again and on came the engine fault, orange triangle and back into limp mode. I’ve just spent £130 at a Citroen garage. Their scanners have come up with the same faults, new tank needed and pressure low. Very frustrating. Any ideas would be welcome. Could the new tank be faulty?
Looking forward to reading responses.

[Sikez2012]

What codes are you getting?
Was the work carried out at Citroen? If so can you not take it back and advise why after replacing what they diagnosed you still have the same fault.
Otherwise your just going to keep paying out changing god knows what until some other part resolves the issue if at all.
And why after replacing the parts you need to keep resetting the fuel system..
Does the car need telling/programming these new parts in to show they are new to enable them to work correctly the car may be running off the old values if they have not been(assuming they need programming etc).

[Sol]

What do you mean by rejuvenating the car? resetting fault codes? This is the oddest story I've heard yet.

The fuel cap has a sensor, when the ECU sees you have refuelled, it commands the DPF additive pump to inject some Eolys fluid into the fuel tank. The only reason it can go into limp mode is wrong fuel pressure or wrong turbo boost but neither are connected to refuelling, or the DPF system.

None of this information you have provided makes sense. Either your understanding of what was done is wrong, or they are telling you nonsense at the garage.

[Tom Wilton]

What do you mean by rejuvenating the car? resetting fault codes? This is the oddest story I've heard yet.

The fuel cap has a sensor, when the ECU sees you have refuelled, it commands the DPF additive pump to inject some Eolys fluid into the fuel tank. The only reason it can go into limp mode is wrong fuel pressure or wrong turbo boost but neither are connected to refuelling, or the DPF system.

None of this information you have provided makes sense. Either your understanding of what was done is wrong, or they are telling you nonsense at the garage.

The code received is P1435 which requires new FAP tank and fluid. This work has been carried out and the code cleared. The car drives fine then until I refill the tank then it goes back into limp mode with the same code given as a diagnosis. It doesn't seem to matter how many miles I do its only when I put fuel in. My mechanic has tried clearing the codes three times now and each time is fine until I refill. The replacement tank and fluid was not carried out by a citreon garage but a very able mechanic. By rejuvenating I meant regenerating the car after work had been carried out. A real mystery. Thanks for your response.

[Mark604]

Do you fill up at the same petrol station every time this has happened?

[Sikez2012]

Are you sure its not the pouch in the tank near the drivers side back wheel that's causing the issue, Eolys or close to that for the emissions,
When you refuel there's a chip on the flap inside(when you open it) which tells the ecu to inject a set amount into the fuel tank and when the ecu i think at about 100,000 miles says its time for a new pouch to be fitted.
This has to be paired up using diagnostics Citroen use DIAG for example, keep clearing the code wont reset it in the ecu and will keep throwing it up each time you refuel because the cars ecu does not know it has been changed.
If this has been carried out then apologies.

[Sol]

What do you mean by rejuvenating the car? resetting fault codes? This is the oddest story I've heard yet.

The fuel cap has a sensor, when the ECU sees you have refuelled, it commands the DPF additive pump to inject some Eolys fluid into the fuel tank. The only reason it can go into limp mode is wrong fuel pressure or wrong turbo boost but neither are connected to refuelling, or the DPF system.

None of this information you have provided makes sense. Either your understanding of what was done is wrong, or they are telling you nonsense at the garage.

The code received is P1435 which requires new FAP tank and fluid. This work has been carried out and the code cleared. The car drives fine then until I refill the tank then it goes back into limp mode with the same code given as a diagnosis. It doesn't seem to matter how many miles I do its only when I put fuel in. My mechanic has tried clearing the codes three times now and each time is fine until I refill. The replacement tank and fluid was not carried out by a citreon garage but a very able mechanic. By rejuvenating I meant regenerating the car after work had been carried out. A real mystery. Thanks for your response.

I'm sorry Tom, I understand now. And as said above, if the tank or pouch and pump are replaced, clearing the codes has zero effect. 

The new fluid level must be coded into the multiplexed additive ECU using Citroen Diagbox software, nothing else will do it.  No matter the competency of the mechanic, this software has to be used. Code clearing OBD equipment does not work for that task. 

If you only clear the codes, it will drop into fault every time you refuel, for ever more.