FAQ
TL;DR: In this C4 Picasso 1.6 HDi case, 2 tools were tried—"Made both DB and AutoCom." Clearing P1446 sticks only after the correct additive-service reset and confirmation. [Elektroda, sly_1978, post #16729181]
Why it matters: This FAQ helps owners and techs fix P1446 after FAP bag/tank work without needless parts swaps.
Quick Facts
- P1446 persisted after entering new bag capacity until the right service task was performed. [Elektroda, maceek16, post #16727597]
- Lexia/Proxia reports "done," yet the fault remains; Diagbox is required. [Elektroda, robi1214, post #16729171]
- OP confirmed using Diagbox and AutoCom during successful reset attempts. [Elektroda, sly_1978, post #16729181]
- Battery disconnect was suggested as a retry aid before re-running the reset. [Elektroda, fructon, post #16729237]
- Harness to the additive dispenser has 4 conductors and is prone to breaks. [Elektroda, bobytempelton, post #18205683]
How do I clear P1446 after replacing the FAP additive bag?
Use Diagbox, run the additive service task, then erase faults. Lexia/Proxia may say "done" but won’t clear P1446. "Diagbox needed." [Elektroda, robi1214, post #16729171]
Do I need to tell the ECU that I replaced the additive bag or tank?
Yes. In Diagbox, declare the replacement so the additive controller updates counters and status. Without that, the engine ECU can keep P1446. [Elektroda, sly_1978, post #18202233]
Which tool works best: Lexia, Proxia, Diagbox, or AutoCom?
Diagbox is the reliable path for clearing P1446 after additive work. Lexia/Proxia reports completion but the code returns. [Elektroda, robi1214, post #16729171]
Is a full refuel required to clear P1446 after bag replacement?
The thread fix focused on performing the correct Diagbox additive task and clearing errors; refueling wasn’t identified as the key step. [Elektroda, sly_1978, post #16729181]
Diagbox says the procedure finished, but the code returns on restart—what next?
Repeat the additive service task, confirm telecoding, then clear faults again. Users reported clearing, restart, and immediate return before proper reset. [Elektroda, Anonymous, post #16737558]
I replaced the entire additive tank and pump; why is P1446 still present?
The additive module can show zero errors while the engine ECU still logs P1446. Clear the engine ECU after declaring the replacement. [Elektroda, k0lega, post #18202264]
What fluid level should appear in live parameters after the fix?
You should see a valid, non-zero additive quantity consistent with a new bag/tank in the parameter list. Verify before clearing faults. [Elektroda, sly_1978, post #18202313]
Could a clogged FAP/DPF alone cause P1446 here?
This discussion points first to the additive system path—declaration, resets, and wiring—before suspecting the filter itself. Check those items. [Elektroda, bobytempelton, post #18205683]
Can wiring issues trigger or sustain P1446?
Yes. The dispenser harness is fragile; it uses 4 wires that often break. Replace or repair the loom if faults persist. [Elektroda, bobytempelton, post #18205683]
Will disconnecting the battery help during the reset process?
It can help you retry from a clean state. Disconnect briefly, reconnect, then rerun the additive service task and clear codes. [Elektroda, fructon, post #16729237]
Why does the code clear, then immediately return when I start the car?
The engine ECU reevaluates the additive system on startup. If declaration or wiring is incomplete, P1446 reappears right away. [Elektroda, k0lega, post #18202264]
What is the FAP additive bag on PSA diesels?
It’s the reservoir holding the particulate-filter additive used for regenerations. Replacements require ECU declaration and service reset. [Elektroda, sly_1978, post #16727494]
Any quick 3-step how-to for the post-replacement reset?
- In Diagbox, declare additive bag/tank replacement and save. 2. Run the additive refill/prime service task. 3. Clear engine faults, cycle ignition, recheck parameters. [Elektroda, robi1214, post #16729171]
What finally worked for the original poster?
Multiple attempts with the right tools were involved; the OP confirmed using Diagbox and AutoCom during the successful resolution. "Made both DB and AutoCom." [Elektroda, sly_1978, post #16729181]
