Q: Ticking noise

Hello. A ticking sound from the engine can be caused by a few different things. Two of the most common causes, as you already figured, are from faulty injectors or an issue with the valve train. If the clicking is due to faulty injectors then the vehicle will likely experience a misfire, or other noticeable performance issues, as a faulty injector will disrupt the air fuel ratio. It may also be possible that the noise is related to the valvetrain. A few things that can cause noise from the valve train are low or dirty oil, excessive valve clearance, or damaged valves or lifters. These issues may also come accompanied with performance issues, that will be more noticeable the more serious the issue. If the check engine light is on then retrieving the trouble codes will likely shed some light on what the issue may be. I would start by trying to determine if the noise is coming from inside or outside of the engine, and go from there. I would also check to make sure that the oil is topped off, and clean. If you are unsure, I would recommend having a professional technician, such as one from YourMechanic, come to your location to diagnose what may be causing the ticking noise.