Engine Desynchronization Due to Loose Timing Chain (1.6 THP Flex/Gasoline Engine)

• Most affected models: C4 Lounge, C4 Cactus, DS3, DS4 and DS5 equipped with the 1.6 Turbo (High Pressure) engine.
• What happens: The engine starts to make a loud metallic noise when starting from cold (similar to a sewing machine or diesel engine). In advanced cases, the car loses power, enters safe mode, and records a fault code related to the correlation between the phase and rotation sensors.

What to check:

1. Current Tensioner: This hydraulic component may lose its load capacity or seize up, leaving the chain slack.
2. Current Guide (Channels): With the chain loose, the plastic guides suffer constant impact, which can cause them to break and generate debris in the crankcase.
3. Oil Pressure and Changes: The system is crucially dependent on oil pressure. Using out-of-specification lubricant (5W30 or 0W30 PSA) or extended oil intervals accelerates wear.

Solution:

• Preventive: Strictly use the oil approved by the vehicle manufacturer and replace it every 7,000 km or 10,000 km at most. Monitor for abnormal noises in the first 30 seconds after starting the engine in the morning.
• Corrective: Replacement of the complete timing kit (updated chain, guides, gears and new generation tensioner). It is essential to collect any broken plastic guide pieces from the oil pan to prevent them from obstructing the oil pickup.