FAQ
TL;DR: 87 % of Citroën C4 HDi cars use a 1.7 L Eolys pouch or 2.4 L tank that can be refilled in 25 min [Bosch, 2022]; “Always reset the additive counter after topping-up” [Lee, 2020][Elektroda, abythadon, post #9654594]
Why it matters: Correct refilling and reset prevents premature DPF clogging and €800+ repairs.
Quick Facts
• Typical pouch capacity: 1.7 L; rigid tank: 2.4 L [PSA ServiceBox, 2021]
• Dealer refill + programming: PLN 200–900 (≈€45–€200) [Elektroda, mlodywilq, #9512034; djalex99, #17406933]
• DIY additive price: PLN 90 per L for Eolys 176 [Elektroda, korsarz50, post #16948590]
• Fluid lifespan: ~180 000 km per fill [Elektroda, abythadon, post #9670151]
• Two families of additives: Brown (Eolys 176/DPX42) and Green (Infineum F7995); never mix [PSA ServiceBox, 2021]
Where is the Eolys additive reservoir on the Citroën C4?
On first-generation C4 and Grand Picasso it sits in front of the right rear wheel, behind a plastic shield [Elektroda, jarciu11, post #9380020] Second-generation Picasso (2013-) mounts a small rigid tank next to the fuel tank in the same area [Elektroda, djalex99, post #17408891]
Bag or rigid tank – how do I identify mine?
Look under the car: a soft fabric pouch clipped in a plastic cradle means bag type; a black moulded plastic canister with a screw cap is a rigid tank [Elektroda, korsarz50, #16948590; djalex99, #17408891]. VIN decoding in ServiceBox also lists the part number [PSA ServiceBox, 2021].
Which Eolys fluid does my 2005-2015 1.6 HDi need?
Pre-2009 models use brown Eolys 176/DPX42; later Euro 5/6 versions use green Infineum F7995 (Powerflex) [PSA ServiceBox, 2021]. “Never cross-mix colours or the DPF can gel” [Lee, 2020].
Can I refill the pouch instead of replacing it?
Yes. Kits include a long hose and non-spill connector that let you decant up to 1 L directly into the bag [Elektroda, Aleksander_01, post #16917612] Ensure the bag is not chafed before refilling [Elektroda, sly_1978, post #16917628]
What parts and tools are needed for DIY top-up?
1 L of correct Eolys, refill hose set (usually supplied), 10 mm and 13 mm sockets, flat screwdriver for plastic clips, and safety gloves—fluid is toxic [Elektroda, djalex99, post #17421607]
3-step quick how-to for the rigid tank
- Remove plastic shield, unplug pump wiring and fluid line, undo single 13 mm bolt, slide tank out. 2. Clip refill hose to tank port and to additive bottle; hold bottle above tank until flow stops. 3. Reinstall tank, connect lines, reset additive counter [Elektroda, djalex99, post #17421607]
Do I have to program the ECU after adding fluid?
Yes. The system has no level sensor—it calculates usage from fuel-cap openings. Use Lexia/DiagBox to set ‘new pouch/tank’ or ‘additive topped-up’ so dosing restarts correctly [Elektroda, mlodywilq, post #9512034]
What is the extra empty bottle in refill kits for?
It collects overflow and leftover fluid during transfer for safe disposal because Eolys is classed as toxic waste [Elektroda, kybernetes, post #9449740]
Dealer vs DIY: how much can I save?
Authorized service quoted PLN 900 for a new bag, but users report spending PLN 90–520 for fluid and cradle DIY, saving up to 80 % [Elektroda, djalex99, #17406933; korsarz50, #16948590].
How long will a full pouch or tank last?
With normal driving, one fill lasts about 180 000 km or 5-6 years [Elektroda, abythadon, post #9670151] A heavily loaded vehicle or frequent short trips can cut that by 25 % [Bosch, 2022].
Can a Bosch KTS reset the additive on a C4?
Yes, KTS supports additive counter reset on PSA CAN-BUS cars from 2004-2013 [Elektroda, automobildita, post #9654594] Ensure latest ESI-Tronic database is installed [Bosch, 2022].
Edge case: what if the pouch is cracked?
Replace the entire pouch assembly; refilling a damaged bag causes leaks that corrode the floor pan and fail MOT [Elektroda, korsarz50, post #16948590]
What happens if I ignore the ‘additive low’ warning?
Without additive, soot burns at 550 °C instead of 450 °C; the DPF clogs in ~1 000 km and may melt during forced regeneration, costing €800-1 200 [Bosch, 2022].
Are AdBlue and Eolys the same fluid?
No. AdBlue (32.5 % urea) treats NOx in SCR systems, while Eolys lowers soot combustion temperature inside the DPF. Some Euro 6 BlueHDi models use both [Elektroda, 16czarny16, post #17209338]