Unlike German diesels that rely purely on exhaust post-injection heat to burn off DPF soot, PSA Peugeot-Citroën (and Stellantis-built Vauxhall) HDi and BlueHDi engines use a fuel-borne cerium/iron catalyst fluid (Eolys) stored in a collapsible underbody pouch (OEM 9678033680 / 1500RZ). Around 70,000–85,000 miles, the dashboard chimes with 'Engine Fault: Repair Needed / Particle Filter Additive Level Too Low'. Here is why replacing the pre-filled 1-litre pouch and checking the electronic thermostat housing (OEM 9827379280) is essential.
1. How the PSA Eolys Pouch (9678033680) Lowers DPF Burn-Off Temperature from 600°C to 450°C
Every time you open the fuel filler cap and add diesel on a Citroën C3, C4, DS3, Berlingo, or Peugeot 207, 208, 2008, or Partner 1.6 HDi / e-HDi, the additive dosing pump injects a few millilitres of fluid from pouch 9678033680 into the main fuel tank. This catalyst bonds with soot particles inside the DPF so they combust at just 450°C instead of 600°C—ideal for British urban traffic.
2. UK Workshop Diagnostic Fault Codes, Symptoms & Root Causes
| Fault Code / Defect | On-Road / MOT Symptom | Root Cause & Permanent Workshop Fix |
|---|---|---|
| P1434 / P1435 | Fuel Additive System — Open Circuit / Multiplexed Additive Pump Fault | Empty collapsed Eolys pouch (9678033680) or airdrawn into the dosing pump. |
| P1446 / P1445 | Additive System: Calculated Additive Level Below Minimum Threshold | Additive counter reached threshold; replace pouch BD1048 and reset counter in ECU & pump module. |
| P0597 / P0128 (2.0 & 2.2 BlueHDi) | Thermostat Heater Control Circuit Open / Coolant Temp Too Low | Failed electronic thermostat housing (OEM 9827379280 — SKU: EN1006) blocking DPF regeneration. |
3. Verified OEM Part Number Cross-Reference & UK Fitment Guide
| OEM Reference | UK Vehicle Application | Component & Workshop Spec |
|---|---|---|
| BD1048 — 9678033680 / 1500RZ / 9678033680 | Citroën C3 II, C4 Cactus, C-Elysée, DS3 & Peugeot 207, 208, 2008, 301 1.6 HDi / e-HDi | Pre-Filled 1-Litre DPF Particulate Additive Fluid Flexible Pouch Kit |
| EN1006 — 9827379280 / 9804160380 | Peugeot Boxer, Citroën Relay, Vauxhall Vivaro/Movano & Fiat 2.0 / 2.2 BlueHDi | Complete Electronic Coolant Thermostat Housing Assembly |
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4. Step-by-Step UK Workshop Fitting Procedure & Torque Specs
- Drop the Underbody Plastic Additive Housing Cover: Ahead of the nearside rear wheel, undo the 10mm nuts and plastic clips holding the lower clam-shell cover.
- Unclip the Quick-Release Coupler & Swap the Pouch: Press the green/white quick-release tab on the dosing pump nozzle, remove the flat empty pouch, and click the new BuyDay BD1048 1-litre pre-filled pouch straight onto the spigot (no messy pouring or bleeding bottles needed!).
- Run the ECU 'Additive Pouch Replacement' Reset Routine: Connect your scanner -> Engine ECU -> Repair / Replacement Parts -> 'Replacement of Additive Pouch / Reservoir' -> Prime pump and reset counter to zero.
5. Master Mechanic Q&A: UK Workshop & MOT Questions Answered
Q: Why is a pre-filled 9678033680 pouch better than refilling an old pouch with a bottle?
Dave Mercer (Master Tech): Old plastic pouches become brittle and crease along their folds, causing pinhole leaks or collapsing onto the suction port. Clicking in a brand-new pre-filled 1-litre pouch (BD1048) takes 10 minutes with zero chemical spills.
Q: How long does a 1-litre 9678033680 DPF additive pouch last?
Dave Mercer (Master Tech): Under normal UK driving conditions, a fresh 1-litre Eolys pouch lasts between 65,000 and 80,000 miles.
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