Rough Idle - Engine Codes - Fuel Canister - £2k Garage Bill!!

[Matchbookfail]

Car: 2017 Plate , Grand C4 Picasso, 1.2l Puretech Engine (130bhp), Auto Gearbox
43K miles, had a new engine under warranty at 23k

We have been having an issue with a rough idle, smelling a bit rich and engine hesitation when coming off throttle.
Got the OBD port checked at that threw up the following issues:

• P2271 - Lambda Sensor (Bank 1 Sensor 2)
  P2196 - Lambda Sensor (Bank 1 Sensor 1)
  U1109 - CAN communication to transmission control
  P0172 - Mixture (Bank 1)

(FYI only one bank on an inline 3 engine )

I took it to my local garage but due to the 'auto gearbox error' they didn't want to try and fix it so recommended I take to the main dealer (which i have a service plan with anyway).

Took to main dealer, they spent 1.5 days diagnosis the issue and have come back with the following:

Our technician has carried out a diagnostic on your vehicle and found fault codes stored that relate to the Fuel System/Supply. After following diagnostic guidance, we have found that fuel has got into the canister which should not contain any liquid fuel at all and is there as a part that absorbs/collects petrol fumes to stop them spreading around the vehicle.

As fuel itself is present in the canister, this means that your vehicle requires repair which includes replacing the fuel tank and the canister and fuel. We have priced this up for you and the repair inclusive of parts, labour and VAT comes to £1925.09.

Speaking to them, this is the fuel canister which should feed fuel vapour back to the fuel tank.

In short, I'm not ready to hand over £2k to fit this without more details, including a breakdown of what parts are actually being replaced!Which is also what i need to get alternative quotes.
I am waiting to hear back but have asked the following:

Has the fuel come from the engine to get to the canister? or back flowed from tank?
What is the root cause? as a result something in the engine is faulty?
Is this a common issue? or something we have done to cause it? ... I certainly would not be wanting to have this every 5.5 years!

Anyone had a similar issue, or a similar cost to fix?

[darbuck]

This is a rich condition. Your car is over fueling most likely a leaking injector, bad spark plug or Coil. None of them are related to cannister.

[xantia_v6]

It is plausible that fuel in the vapour cannister is being sucked into the engine via the purge valve.

It should be fairly easy to check by finding the pipe to the purge valve, which probably runs next to the fuel line above the right hand engine mount (the larger of the two pipes), and tamporarily disconnecting it (blocking off the end going to the engine).

If the engine runs ok (perhaps a bit smelly) withe the vapour line disconnected, then the diagnosis is correct.

I think that the vapour cannister is part of the fuel tank assembly on some PSA vehicles, which would explain the quote for replacing the tank, but it is not 100% sure that having fuel in the cannister should permanently destroy it. It could be that draining the cannister using a vacuum pump to evaporate the contents will restore it.

[MattBLancs]

Not sure on the specifics of this car, but would be very surprised if the fuel return / vent connection was below the fuel level - as such it shouldn't be able to suck fuel back up the line, should it??

My understanding is lambda codes are often nowt to do with the lambda itself, it the rich condition that is being picked up and the lambda "being blamed" by the ECU.


Many years ago a mate and I were working on a Corsa, we managed to mix up the fuel / return / vent lines on reassembly (all identical push in connectors - nice error trap, swapping male and female orientation on one pair would have helped reduce chances of this)

That filled the (front wing mounted in this case) charcoal canister filter with fuel. From memory I think it ran pretty terrible too but I'm telling a tale from perhaps 15 years ago...
We swapped the connections and it was fine after that.

Just raising on the basis of "check the silly things first"
I e. It's not had a new fuel filter / need for those pipes to be messed with in the recent past, has it?

Surprised they are integral to the tank.

[Matchbookfail]

Thanks for your replies @darbuck @xantia_v6 @MattBLancs

An update: First updated pricing...
Petrol vapours absorber/canister - £176.29
Fuel tank - £1037.29 - This doesn't include the fuel pump or fuel gauge equip in the tank!!!
Fuel tank seal- £14.01
Fuel tank ring - £8.89

Total parts - £1236.48
Total labour - £504.00
Total - £1740.48

Interestingly they can't tell me why the price as has been reduced. And their labour rate is £100 an hour, so it's 4-5 hours of labour for all the work.

I have been told and had confirmed by another garage the following:
Fuel vapour from the tank goes out of the tank, through the fuel canister, then to the engine to get burned, so all fuel (liquid or vapour) is burnt in the engine.
So the one-way valve between the tank and canister has let the liquid fuel by in the correct direction, but it isn't designed for liquid.

I have come to the conclusion that they are changing the fuel tank, and my fuel as a precaution... because they don't know if there is anything wrong with them...
I am currently waiting to see if Citroen UK want to contribute towards the repair, apparently, that's a thing

Frustratingly there are a number of additional costs if I move it to another garage (2x diagnostic cost, flatbed transport cost etc) so I think im stuck with the current garage.

[MattBLancs]

My understanding of fuel vapour system:

Undesirable / hypothetically unsafe to vent fuel vapour to atmosphere and fuel tank can't just be sealed - changing in temperature leading to pressure building up in tank.

Hence, when engine off, tank is venting via a carbon filter (reduces smells) to atmosphere = all is well.

When engine is running, fumes instead fed to inlet manifold when they enter the engine and are burnt off. No need for taking the smell out so wouldn't pass through the carbon filter in this mode.

Changeover valve to flick between the above two states.

Given the fuel cannister seems to be a separate part, I'm with you in that the tank swap seems to be for no obvious reason. Unless it's in a "we've touched it so will fit new" justification if the carbon filter is in / hidden by the fuel tank. There's fun and games to be had when removing and refitting the tank seal and ring (also itemised) so maybe the tank part cost is being ignored and just stick a new one on seen as way forward.

Marc, can you confirm if the carbon canister is in / hidden by the fuel tank?

Thanks

Matt

[darbuck]

That sounds like a bit of shafting going on to me, I would be looking for a better reason to change tank like it has a hole in it. The carbon canister is connected to the top of the fuel neck near the cap. Did you ever fill the car to the neck? if so fuel could have gotten into the cannister via the vent pipe.

[darbuck]

the cannister is not in the tank have a look at this
download/file.php?id=14628&mode=view

[androa]

I seem to be having the same issue on my 2017 C4 Grand Picasso.

Also here the garage gives an offer that includes changing the gas tank, under the assumption that the charcoal cannister is inside the gas tank.

They say it is a known problem for Citroen and is described with the Technical Service Bulletin B1HW01H5Q0, but I've not been able to get my hands on that TSB. Is there anyone that has access to it?

[androa]

Another theory I have for why they want to change the gas tank itself is that I believe there is a one-way valve inside the tank, protecting the canister from overflow of gasoline from the tank.

This is seemingly a simple floating valve that closes off by the level of gas. This probably gets stuck in the open position and then does not close the flow of gasoline from the tank to the canister.

If I never fill the car to more than 3/4 of a full tank, it exhibits none of the issues it is having with a full tank.

[juliusre]

Another theory I have for why they want to change the gas tank itself is that I believe there is a one-way valve inside the tank, protecting the canister from overflow of gasoline from the tank.

This is seemingly a simple floating valve that closes off by the level of gas. This probably gets stuck in the open position and then does not close the flow of gasoline from the tank to the canister.

If I never fill the car to more than 3/4 of a full tank, it exhibits none of the issues it is having with a full tank.

Hi, I was wondering if you could share updates on the resolution of this issue. Did you end up changing the petrol tank?

I have same issue - filled up my C4 Grand Picasso full (2017, 1.2 petrol) and after about 50 km found a puddle of fuel near the left rear door a few hours later, black box (ventilation canister) was dripping fuel. Since then car had issues mainly with 75-100% full tank - rough idle, loss of power, sometimes complete engine stalls.

Citroen says the problem is with the tank ventilation system - "the vent hose or valve may be blocked and the charcoal canister is damaged". They suggest replacing both the fuel tank and the canister, which is quoted at around 3700 eur.