2023 Passat 206TSI B8 R-Line Wagon; Petrol tank knocking, and high pressure

Hi,

2023 Passat 206TSI B8 R-Line Wagon

Yesterday, I noticed a knocking sound coming from the petrol tank area, after driving the car. This is the first time it happened and it was 35 degrees yesterday for reference.

I opened the fuel cap and a rush of air / vapour came out which was unusual. This stopped the knocking. Driving again, the same thing happened, and the same cap removal stopped it.

I looked into it and apparently it might be related to the purge valve, but I am getting no codes when scanning, and there is no engine light on.

Anyone else had this issue? If so, what was the cause / fix, etc.?

The high heat/high humidity the past few days might be playing a part here, but the charcoal canister and evap purge valve should be releasing any excess pressure and fumes from the petrol tank.