Code
C918
CITROEN
C — Chassis
Fault on the right-hand front audio output: Open circuit
AI status
Completed
Completed
100%
Causes
- Broken or disconnected speaker wire between right front speaker and amplifier/module
- Faulty right front speaker (open voice coil)
- Poor/cracked connector or corroded terminals at speaker or amplifier
- Defective amplifier/audio module output stage
- Blown related fuse or failed power/ground to amplifier
- Harness damage (pinched, chafed, rodent chew) or poor solder joint
Symptoms
- No sound from right-front speaker
- Channel imbalance (missing front-right audio)
- Distortion or intermittent sound from right-front location
- Audio system displays speaker fault or mutes affected channel
- Fault stored in audio/amplifier control module (C918)
What to check
- Scan vehicle for stored audio/module faults and note freeze/frame data
- Visually inspect speaker, connectors, and door harness for damage or corrosion
- Check related fuses and amplifier power/ground circuits
- Measure DC resistance of the right-front speaker at the speaker terminals (expected typically 2–8 Ω depending on speaker)
- Verify continuity between amplifier output pin and speaker terminal (expect low resistance)
- Listen for audio output during a speaker test (use low volume to avoid damage)
Signal parameters
- Expected speaker impedance: typically 2–8 Ω (manufacturer dependent)
- Measured resistance at speaker terminals: low finite value (not infinite)
- Continuity: closed circuit between amplifier output pin and speaker terminal (low ohms)
- Amplifier output with audio: AC waveform centered near 0 V (coupled), several volts peak-to-peak depending on volume
- Open-circuit symptom: infinite resistance / no continuity; no AC waveform present at speaker terminal when driven
Diagnostic algorithm
- Confirm complaint and reproduce: play audio and verify no sound from right-front speaker; note any intermittency.
- Scan for codes: read audio/amplifier module faults and relevant bus errors; record fault occurrence conditions.
- Visual inspection: open door trim if needed and inspect speaker, connector, and wiring for damage/corrosion; check door hinge area for broken wires.
- Check fuses/power/ground: verify amplifier module supply and ground circuits are present and within spec.
- Measure speaker resistance at the speaker terminals with the connector disconnected from the amplifier. If resistance is infinite, suspect open speaker or wiring to speaker.
- Measure continuity between amplifier output pin (at the module connector) and speaker terminal while manipulating the harness; if open, locate and repair break (often at door hinge).
- If speaker and wiring have continuity, use an audio source or diagnostic unit to command audio output and probe amplifier output with an oscilloscope or audio probe to confirm signal. No signal with good supply/ground suggests amplifier/module fault.
- Swap a known-good speaker or swap channels (if vehicle design allows) to see if fault follows the speaker. If fault remains on same channel, suspect amplifier/module.
- Repair or replace failed component (repair wiring, replace speaker, or replace amplifier/module). Reassemble and clear codes.
- Verify repair by re-running tests: confirm sound from right-front speaker across volume range and clear stored faults; road-test to confirm no recurrence.
Likely causes
- Open/disconnected speaker connector at the right front door/speaker
- Speaker voice coil is open (infinite resistance) from damage
- Broken wire in the door harness (common at hinge area)
- Amplifier output channel failed (open when driven)
- Blown inline speaker fuse or missing ground connection
Fault status
Status
Open circuit detected on right front audio output — no continuity or signal present at right-front speaker output.
Repair difficulty: Medium
Diagnostic time: 0.5-1.5 hours
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