rotten egg smell when I turn heater on?

Hello,

Rotten egg smell in the vehicle typically indicates some type malfunction in the fuel system. A worn out damaged catalytic converter, fuel pressure regulator can produce sulfur gas and that can enter the vehicle.

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

Keep in mind that leaking heater core will have a sweet smell to it for the coolant.

First do an inspection of under hood fuel components. Check the fuel rails and the fuel regulator. Look for any leak or damage to the components.

Also it will be a good idea to scan the vehicle for any trouble codes. Typically with a bad catalytic converter the check engine light will be illuminated.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

I have attached the fuel system diagrams under hood.

Please let me know of any questions.
Thank you.