I've got a 2019 Mazda CX-9 that's been pretty much bulletproof since I bought it, but over the past month or so I've noticed this high-pitched whistle coming from the engine bay whenever I accelerate, and it's starting to drive me crazy trying to figure out what it is. At first I thought it might be a vacuum leak because the sound changes with engine load, but I've checked all the hoses I can see and nothing looks obviously cracked or loose. I also considered that it could be a belt issue, but the sound doesn't seem to change when I turn the steering wheel or use the AC, so I'm leaning more towards something like an intake gasket or maybe even the turbo if these engines have one – though I'm not actually sure if the CX-9 is turbocharged or not because I bought it used and I never really checked. The dealership quoted me a fortune just to do a diagnostic, and honestly I'm not keen on paying those rates for something that might end up being a simple fix. I've heard good things about a few independent shops in the capital that know their way around Japanese cars, and I've been meaning to find a place that actually takes the time to diagnose rather than just guessing and replacing parts. A mate of mine who drives a Mazda 6 mentioned something about Expert Mazda Repair By 800Sayara Abu Dhabi and said they actually found the issue with his car after two other shops couldn't figure it out. Has anyone here had a similar whistling noise on their CX-9 and found it to be something specific, or am I just going to have to accept that I need to take it in and pay for a proper diagnostic? I'm hoping it's not something serious because I really love this car and I want to keep it for several more years, but I also don't want to ignore what might be an early warning sign of a bigger problem. Any advice from fellow Mazda owners would be massively appreciated right now because I feel like I'm going in circles trying to self-diagnose this thing.