Doctor Diesel

Reservoir gone to the dogs

Dear Doc,

I have a five-year-old Citroën C4 1.6HDi. On Christmas Eve, while on the motorway, a whole host of warning lights on the dashboard manifested themselves, and to cut a long story short, I have ended up having to have a new AdBlue reservoir fitted.

The cost of this repair would have been over £1,000, but with the help of my Citroën Authorised Repairer, who managed to get a gesture of goodwill contribution from the manufacturer, my bill came to around £800.

From doing a bit of investigation, it is clear that the failure of AdBlue reservoirs in the C4 family (Citroën C4 and Cactus and DS4), is not uncommon, and so the reservoirs, as fitted, cannot be fit for purpose. A very expensive component, such as these reservoirs, obviously should not fail in cars of my age and indeed younger.

PSA must be aware of this situation. The question then is why have they not carried out a recall and replaced these reservoirs, as they should be morally and ethically obliged to do? A stupid question, of course! It would cost them a fortune. So, far better for them to do nothing, and leave it to the poor unsuspecting owner to pick up the bill for putting things right when their reservoir fails.

I would be grateful for your views, please. Also, is there anything I can do to get a bigger contribution for the cost of replacement from Citroën over and above the £200 gesture of goodwill they have already made?


Nick Parker

Hello Nick,

Thanks for getting in touch. Sorry that you’ve had to fork out for a new AdBlue reservoir – spending £800 on a replacement part is the last thing anyone needs at the moment. It’ll come as no consolation to discover that you’re not alone. There are many cases of owners having to replace the tanks, and it affects a number of cars within the PSA stable.

The problem could have been avoided with a new filler cap. Some owners were contacted by dealers to notify them of a safety recall. The letter said: “On the affected vehicles check and, if necessary, replace the filler cap of the Selective Catalytic Reduction (SCR) system reservoir. This campaign is in order to improve the venting of the reservoir, so as to avoid the lighting of a warning lamp on the dashboard and not being able to start the engine. In some cases, the reservoir will have to be replaced.” Later cars had the new cap fitted from new, while cars covered by the manufacturer’s warranty would have received a cap and/or tank at no cost to the owner.

In short, the vent valve system didn’t work, which meant the urea pump had to work doubly hard. Eventually, the pump would fail, resulting in the errors you saw on the dashboard. PSA fixed the issue by using an AdBlue cap fitted with a small pressure release valve. If caught in time, a new cap would fix the issue. If not, a new tank was required. Unfortunately for you, your C4 missed the recall and is now outside of the warranty period.

Sorting the issue is expensive, not least because there’s no part number just for the pump. It means that you have to buy an entire reservoir. The only good news is that it’s a quick job, but this won’t provide a crumb of comfort for you. A little research shows that one owner managed to convince Peugeot to pay 50 per cent of the cost on an out-of-warranty car. Others have paid the full price.

I’d use the £200 gesture of goodwill as a kind of admittance of guilt. Argue the point about the fact that the problem should have been fixed under warranty as a recall – it’s not your fault that the issue was missed. Had you not fixed the problem, I would have recommended sourcing a reservoir from a salvage car, although this might have taken a few weeks to find.

Contact Citroën customer service with your complaint. I agree that this problem should have been fixed as a matter of course. I do know that some cars were fixed when they were brought in for their annual service and that later cars are unaffected by the problem.

Good luck, please keep me posted.


2 Responses

  1. Same problem with my daughters 4 cactus Urea light problem requiring new adblue tank an NOx sensor car is 2015 registered and Citroen state as the car is over years old they cannot offer any assistance with the cost of repair, the car has only just 60000 on clock.
    The car has Been in the Citroen garage since 13th Jan, and they cannot say when any replacement part can be sourced., cost will be in the region of 1600/1800,
    Have complained twice to Customer care department, and intend to do so again over the lack of spare parts.

    1. Does the car have a full Citroen main dealer service history? If it does, then there might be more sway. But with the car being 7/8 years old, it is way outside of the original 3 year warranty. I’m not sure there are any or even many manufacturers that would contribute to the cost. The lack of spare parts is a worry though, and I could speak to Citroen to speed up the parts. Drop me a line with the registration number and details to my e-mail address at and I’ll speak to my contact at Citroen on your behalf.

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