A misreading tachometer usually won’t directly affect the turbo or wastegate. The tachometer measures engine speed, and while it’s linked to the ECU, it doesn’t control the turbo or wastegate.

However, if the tach is reading wrong, it could indicate an issue with the engine’s sensors or wiring, which might affect how the ECU manages things like turbo boost. It’s a good idea to fix the tach issue, but it likely won’t cause damage to the turbo directly.