Bluetooth mic input volume

A few years ago I bought an aftermarket Bluetooth kit for my 2006 Mazda 3. It can be finicky on connection but generally once it’s connected it works just great for playing podcasts or music in the car.

However, while I successfully used Siri with it early on (well… as successfully as Siri ever is) I have lately not been able to get Siri to even respond. A couple of weeks ago I sat in the car in the garage, without the engine running, and tried a voice recording with the Voice Memo app. The microphone does hear me, but my voice is quite faint. If that’s all it’s getting, it’s no wonder Siri doesn’t hear me at anything less than a yell when the engine is running and there is road noise.

I just found this four year old tip which I tried today, also sitting in the car in the garage with the engine off, and all I could do was make it worse. I have long had my iPhone volume set to maximum for that device, so I can simply control it with the car’s volume controls on the steering wheel.

So it seems from that tip that something has gone awry with my microphone setup, but my gut instinct says it would either work or not work, or maybe have interference. It’s perfectly clear, it just sounds like I’m sitting in the back of a large van trying to be heard at the front. I’m not. My mouth is only about 300mm from the microphone.

Does anyone have any thoughts on iPhone settings/tips/tricks to either address this issue, or perhaps other tests I can try?