Accent 1.4L A/T Engine Knock Now Due to CVVT Defect. (According sa Casa)

[roydok]

My sister currently owns a 2010 Hyundai Accent 1.4L A/T. This car belongs to the ones who experienced the now recognized engine knocks. She first experienced the engine knock within the the car's 1,000 km Odo reading. Currently the car's mileage is at 20,000 km+. She went through the whole process of ECU software updates, usual checks, etc... After the last update she was advised to only use Shell V-Power Nitro gas (97 RON). Still the engine knock persists and now together with percieved low power and higher fuel consumption not present before. After bringing it again sa casa sabi naman ay baka daw defective ang CVVT kaya kailangan palitan ito. Problem is it will take daw a long time to order parts from Korea.

In your expert opinion: Can engine knocks be caused by a defective CVVT?

Thank you very much.