Hello, I recently bought 2003 bmw m3 which still has about one month warranty. When the car is cold and revved to 2500-3000 rpm there is a metallic sound coming from the engine bay, and my friend which is a mechanic says that the valve train is loud.
If something is wrong with the valve train would the computer register that?
If there are no codes, and the valve train is still loud is bmw required to fix it through the warranty?
Thanks a lot

These engine make alot of noise due to the solid lifters and the loud piezo fuel injectors. It could be possible that your car needs a valve adjustment, but they are not going to do that unless you pay them $1000 or if the car is still covered under the schedule maintanence AND it is asking for maintance now.

Check the owners manual... it will tell you all about the service indicator and when to take the car in for service.