Peugeot 807 check engine light and crankshaft sensor

Those symptoms do point to engine synchronization. Has the timing belt been inspected recently? A degraded or improperly installed timing belt can cause such problems. Or what about the cam sensor?

Timing belt was replaced 40000 km ago. Should I inspect it given the mileage? Could a faulty cam sensor trigger similar symptoms related to the crankshaft to camshaft reference value?

At 40000 km, the timing belt should be good, but check to rule it out. Yes, a faulty cam sensor can cause issues with the crankshaft to camshaft reference value. Given the complexity, consult a qualified mechanic for diagnosis and repair.

I visited a local workshop. The crankshaft sensor was defective. After replacement, engine performance returned to normal. Total repair cost was 340€. Thanks for pointing me in the right direction!