Code
C924
CITROEN
C — Chassis
Fault between the HiFi amplifier and the radio: Open circuit
AI status
Completed
Completed
100%
Causes
- Broken or disconnected wiring between radio and amplifier
- Corroded or poorly seated connector pins at radio or amplifier
- Blown fuse or faulty power/ground feed to amplifier or radio
- Failed HiFi amplifier or radio head unit
- Damaged communication bus (CAN/LIN/MOST) or wiring harness
- Previous repairs with improper connector mating or damaged loom
Symptoms
- No sound or intermittent sound from speakers
- Unit reports “amplifier missing” or similar message on infotainment display
- Certain speakers silent while others work (if amplifier partially functional)
- Radio control of amplifier functions unavailable
- Related audio system fault codes stored
What to check
- Read extended fault memory with a dealer-level or professional diagnostic scanner; record freeze-frame and associated faults
- Visually inspect amplifier and radio connectors for corrosion, bent pins, moisture or damage
- Check fuses and fusible links for radio and amplifier power circuits
- Verify amplifier and radio both have proper 12 V supply with ignition on (see signal parameters)
- Verify good ground at amplifier and radio mounting/ground strap
- Check continuity of the wiring harness between radio and amplifier connectors (communication and power lines)
Signal parameters
- Amplifier and radio supply voltage (ignition on): ~11–14 V
- Ground continuity: near 0 Ω between unit ground and chassis (
- CAN/LIN idle voltage (where used): approx. 2.5 V (verify with vehicle-specific data)
- Speaker line impedance: typically 2–8 Ω each (no short to battery/ground)
- Communication line continuity: low resistance between radio and amplifier connectors; no open circuit
Diagnostic algorithm
- Connect diagnostic scanner and read stored and live data for audio modules; note any linked codes
- Verify power and ground at both the radio connector and the amplifier connector with ignition on
- Inspect connectors and harness for corrosion, bent pins, water ingress and secure mating; repair or clean as required
- Check relevant fuses and relays; replace blown fuses and investigate cause if reoccurs
- Perform continuity check of the communication/data wires between radio and amplifier; repair any open circuits or high resistance
- If continuity is good, verify communication signals with oscilloscope or scanner (module acknowledges, messages present); if no communication, trace upstream/back to control module
- If wiring and connectors are good but fault persists, swap in a known-good amplifier or head unit (if available) to confirm component failure
- After repairs, clear fault codes and perform functional test of audio system; monitor for reappearance of C924
Likely causes
- Disconnected/loose connector at amplifier or radio
- Wiring damage (pinched, chafed or broken) in harness between units
- Faulty amplifier or head unit
Fault status
Status
Open circuit detected between radio and HiFi amplifier communication/power wiring — amplifier not reachable.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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