P1435 on a Citroën: Berlingo, C4, C5, Dispatch and Relay

Citroën and the additive particulate filter

PSA, the group behind Peugeot and Citroën, brought the additive-assisted diesel particulate filter to production cars in 2000 on the Peugeot 607. Citroën followed soon after, with the C5 among the early models to use it. The idea was simple. A cerium-based fuel additive, sold as Eolys, is dosed into the diesel tank at every refuel. Once it is in the fuel, it ends up in the soot trapped in the filter and lets that soot burn at roughly 450°C instead of about 600°C.

That lower burn temperature is why the system worked well in ordinary driving. It also created a dependency. If the additive stops arriving, the filter can still regenerate in some conditions, but far less reliably. Citroën calls the filter the FAP, from the French filtre à particules, and you will see that term on the dash and in the handbook.

Early Citroën systems had a rigid additive tank and a simpler pump. Later cars, from around 2010, moved to a flexible pouch inside a rigid housing and a multiplexed pump that communicates over CAN. P1435 belongs to that later, networked type. We confirm which system your car has by VIN, because the fluids and parts are not interchangeable between generations.

Which Citroën models are affected

Not every Citroën diesel has an additive tank. These are the families where we see P1435 most often. We always confirm the fitted system by VIN.

• Berlingo and Berlingo Multispace

  Common on 1.6 HDi and 1.6 BlueHDi vans and people carriers. Berlingos do a lot of short urban trips, so a filter that loses its additive help clogs quickly.

• C4, C4 Picasso and Grand C4 Picasso

  The 1.6 and 2.0 HDi and BlueHDi engines are the ones to look at. The pump sits near the fuel tank under the rear of the car, a wet and salty place in winter.

• C5 and C5 Tourer

  A long-running platform with the 2.0 HDi and 2.2 HDi. Age matters here: older cars may have the earlier rigid-tank design and ageing wiring.

• Dispatch and Relay

  Hard-working vans with high mileage and lots of stop-start use. Relay installations vary by engine and year, so a VIN check comes first. See our Relay AdBlue page if the van also carries an SCR system.

• DS 3, DS 4 and DS 5

  Models from the same era that share PSA diesel engines and additive hardware. The same code and the same wiring weak points apply.

• Newer 1.5 BlueHDi cars

  The 1.5 BlueHDi (DV5), from around 2018, generally does not use an additive tank. If your car has one, P1435 is unlikely, and we look elsewhere.

Citroën dash messages that go with P1435

The wording changes by model and year, but these are the ones drivers report.

• Engine fault or anti-pollution fault

  A general warning with the engine management light. It can appear as soon as the code stores, with no change in how the car drives.

• "Risk of particle filter blocking"

  The classic message once dosing has stopped and the filter is loading. The car may ask for a sustained drive at speed to burn off soot.

• Additive level low

  A different issue: the additive is running out, or the counter thinks it is. Often shown with codes such as P15B3. A refill and a counter reset are needed, not a pump.

• Power reduced

  The ECU limits power when back-pressure or soot mass gets high. The car drives, but slowly and with noticeably less response.

What goes wrong on Citroën cars

The pump connector and loom run under the car on most models, close to the fuel tank and exhaust. Winter spray, a pothole or a visit to a garage for exhaust work are all enough to start trouble. The commonest fault we find on Citroëns is a corroded or water-logged pump plug. Chafed CAN wires come second.

Citroën vans take more punishment. A Relay or Dispatch in daily trade use sees mud, gravel and kerbs, and the pump connector can be hit or pulled. We check the wiring first on every van and car, then prove the pump with a commanded test before replacing it.

Citroën Eolys and AdBlue: two systems, two tanks

Citroën cars from around 2014 onwards often carry two fluid systems at once. Eolys goes into the diesel to help the particle filter. AdBlue goes into a separate tank and is sprayed into the exhaust to reduce NOx. Each has its own pump, its own warnings and its own codes.

P1435 is the Eolys side. If your Berlingo, C4 or Relay also shows an AdBlue countdown, that is a second job with different parts, and we can look at both in one visit. A top-up of one fluid cannot cure a fault in the other.

How we diagnose P1435 on a Citroën

We work at your vehicle with manufacturer-level equipment. The system is identified first, then tested, then repaired.

• VIN and engine identification

  We confirm the engine code and whether your Citroën has an Eolys system, an AdBlue system or both. That decides the pump type and the fluid.

• Full module scan

  A scan across all modules, not just the engine ECU, shows whether U0118 or FEB0 are present as well and which module reported them first.

• Additive live data

  We read the additive counter, the refuel detection flag, soot mass and differential pressure. This shows whether the pump dosed at the last fill and how far the filter has loaded.

• Actuator test on the pump

  A command from the tool makes the pump run. If it responds, the pump is working and the fault sits in the wiring or supply.

• Measurements at the connector

  We check supply, earth and the CAN lines at the pump plug, under load. Numbers decide whether a pump is needed.

• Look under the car

  We inspect the plug, loom, additive housing and lines for damage, leaks and corrosion, particularly where the loom crosses the subframe and tank straps.

Citroën P1435 repair: what we do and what it costs

We diagnose first, then give you a fixed price before any work starts. No fix, no fee on the agreed outcome.

We are mobile and come to your drive, yard, depot or roadside, 6am to 9pm, seven days a week including bank holidays. Fleet customers with Berlingos, Dispatches and Relays can book several vans in a day. We give a written warranty on the repair.

• Connector and loom repair

  Terminals cleaned or replaced, wires repaired with sealed joints and the loom re-secured clear of the exhaust and subframe.

• Additive pump or pouch housing

  Fitted only once the electrics are proved. The new part is primed, coded and tested.

• Correct Eolys fluid and counter reset

  We use the additive that matches your system by VIN and reset the ECU counter so the dash message clears.

• Regeneration and test drive

  If soot has built up, we run a service regeneration and road test to confirm the codes stay away.

• Mobile diagnosis and simple repair: From £249 Callout, live-data diagnosis and fixes such as a connector or wiring repair.
• Additive pump or pouch tank assembly: Fixed price after diagnosis Confirmed against your VIN before we quote.
• Service regeneration: Quoted on the day Needed only if soot loading is high.

P1435 questions

Does my Citroën Berlingo have an Eolys additive tank?

Many 1.6 HDi and 1.6 BlueHDi Berlingos do, but not all. Petrol models and some newer diesels do not. We check the VIN to confirm before any work.

Is P1435 common on the Citroën C4 Picasso?

Yes, on diesel versions fitted with the additive system. The pump and plug sit low near the rear of the car, so wet roads and salt cause connector faults.

My Citroën says particle filter additive level too low. Is that P1435?

Not necessarily. A low additive message is usually a level or counter code, such as P15B3, while P1435 is a pump or network fault. They can appear together, so both are tested.

Can a Citroën Relay or Dispatch be fixed at the roadside?

Often yes. Diagnosis and connector or wiring repairs can be done where the van stands. If a part needs ordering, we agree the price and return to fit it.

Did Citroën always use Eolys?

PSA has used it since the early 2000s, when the additive DPF launched on the 607 and then the C5. Later designs changed the tank and pump, and the 1.5 BlueHDi generally dropped the additive tank.

Will a main dealer be the only option for P1435?

No. We use manufacturer-level diagnostic equipment, test the whole circuit and give a fixed price. You do not need to take the car to a garage.