Renault Spider Knock Sensor Issue

Sounds like a knock sensor problem. Have you checked the wiring harness and connector for corrosion or damage? Even a small wire break can cause this.

What specific points should I inspect on the wiring harness and connector to be thorough?

Check the connector terminals are clean and making good contact. Look for cracks or fraying in the wire insulation, especially near the connector and ECU. If unsure, consider a workshop.

Thanks, that's helpful. I'll probably take it to a workshop; repair should be around 95€. Thanks!