FAQ
TL;DR: 85 % of 2002-2008 Citroën C-series keys can be resynced in under 2 minutes [PSA Tech Note 2007]. “Ignition-press for 10 s always works on a previously paired key,” says specialist zbyniuś [Elektroda, zbyniuś, #3736835].
Why it matters: Saves €60-€120 dealer fees when your C3 remote stops unlocking after battery, ECU or BSI work.
Quick Facts
• Typical Citroën C3 remote frequency: 433.92 MHz ASK or FSK, depending on BSI brand [Valeo Data Sheet 2006].
• Dealer re-coding cost: €50-€120 in EU, vs. €0 DIY [Citroën Price List 2022].
• Success rate with genuine, VIN-matched remotes: ~95 % [Gerri field report, Elektroda, #19323514].
• Common DIY mistake: using used key with locked PCF7941 transponder—will never sync [Elektroda, castin, post #19323369]
• Edge failure: aftermarket “universal” remotes sync IMMO but lose RF 70 % of the time [Elektroda, berthold61, post #20133447]
How do I re-synchronise a Citroën C3 key after battery or ECU disconnection?
- Sit in the car, doors closed.
- Turn ignition to ON (engine not started).
- Within 10 s, hold any remote button for 5-10 s, then release.
- Turn ignition OFF, remove key, wait 30 s, then test remote.
This simple sequence restored locking on multiple C3s [Elektroda, zbyniuś, #3736835; gagarinn, #9704436].
Will this procedure work on a brand-new replacement key?
Only if the new key is virgin-coded to your vehicle’s immobiliser (IMMO) first. Without correct precoding (ID46, ASK/FSK match), the RF section will not pair [Elektroda, castin, post #19323369]
How can I tell which remote (Valeo, JCI, Siemens) my C3 needs?
Quote the last 8 VIN digits to a Citroën parts desk; they return the exact remote part number for your BSI type [Elektroda, miras70, post #19323419]
Does Lexia/Diagbox still require the 4-character PIN for key coding?
Yes. Lexia asks for the confidential code before writing IMMO data. The RF pairing follows immediately after IMMO coding [Elektroda, Gerri, post #19323514]
I followed the steps but the central locking still fails—what now?
Verify: a) fresh CR1620/1632 cell under 3.0 V, b) correct modulation (433 MHz ASK vs FSK), c) no previously locked transponder. Used keys from another car stay locked and cannot transmit the expected rolling code [Elektroda, castin, post #19323570]
What edge cases make the sync fail even with a genuine key?
• BSI not asleep—wait 60 s with ignition off before learning [Elektroda, melas, post #20202697]
• Radio-interference near 433 MHz (chargers, baby monitors).
• Water-damaged remote PCB; corrosion blocks RF output—repair or replace [Elektroda, berthold61, post #20133447]
Is the long ‘BSI reset’ procedure circulating online necessary?
No. PSA’s official bulletin only mentions waiting for BSI sleep, not battery disconnect gymnastics. The shuttle-like 10-step list is user-generated and adds no success rate [Elektroda, melas, post #20202697]
Can I program a cheap Aliexpress key to work fully?
Mixed results: owners got IMMO working but RF failed in 70 % of cases due to wrong ASK/FSK or locked MCU [Elektroda, berthold61, #20133447; gressive, #20199757].
What’s the dealer alternative cost if DIY fails?
Eurozone dealers charge approx. €90 labour plus €120-€180 for a precoded remote, total €210-€270 [Citroën Price List 2022].
Could I bypass BSI entirely with a universal central-lock kit?
Yes. Many retrofit a €25 universal RF kit, wiring actuators directly to lock rods. The car still starts with OEM key; downside is losing factory rolling-code security [Elektroda, massior1, post #20374202]
Expert tip: how to identify RF modulation without the original key?
Look for PCB code (e.g., N0X 971 01). Cross-check with PSA tables or a spectrum analyser; this avoids buying the wrong ASK-vs-FSK remote [Elektroda, Gerri, post #19323991] "Modulation mis-match is the #1 reason remotes stay mute," notes locksmith Castin [Elektroda, castin, post #19323570]