Fluence VANOS Solenoid Issue

The symptoms you describe certainly point towards a VANOS malfunction. Given the Renault Fluence's variable valve timing system, a defective inlet camshaft solenoid valve is a highly probable cause. Prior to condemning the solenoid, I would recommend a thorough inspection of the electrical connections and wiring harness leading to the valve. A voltage drop test under load can reveal a power supply issue. Additionally, consider an engine flush, as oil sludge can impede the valve's operation.

Thanks! The electrical checks are a good call. What voltage readings should I be looking for at the solenoid connector? And if sludge is the culprit, would a simple oil change suffice, or is a more aggressive flush needed?

Under normal operating conditions, you should observe a stable voltage reading close to the battery voltage (approximately 12-14V) at the solenoid connector when the engine is running. A significant drop indicates a wiring or power supply issue. Regarding sludge, a single oil change may prove insufficient. I advise using a dedicated engine flush product, followed by an oil and filter change using a high-quality synthetic oil with enhanced detergent properties. However, if the problem persists, I suggest consulting a qualified technician for a comprehensive diagnosis and repair, as internal engine damage cannot be ruled out.

Thanks a million for the detailed info! I did the electrical checks and found some corrosion on the connector. Cleaned it up, and the light's gone! Still going to do a flush as you recommended. The mechanic confirmed it was the VANOS solenoid and fixed it for 250€. Problem solved!