Mazda Commercial Range

Sometimes head units need a reboot or a return-to-factory-settings button to be pressed. Often, there will be a tiny hole somewhere on the face of the head unit. Into this, you insert a thin piece of wire or a toothpick (or similar) and press just hard enough for the screen to go blank and the unit to reboot. It sounds like you’re using the factory Mazda reversing camera with an aftermarket head unit, so you may need to visit a car audio specialist to get it all working together.

Changing a car’s battery can often be enough to scramble the settings on things like cameras and stereos. You may need to find the security code for the head unit to make it all work properly, too.

The automatic transmission is a mysterious, marvellous piece of equipment that manages to work almost in spite of its complexity. Guessing at a problem like this is fraught with danger, so the best advice is to get the vehicle to a transmission specialist, download the fault codes and see if they give the technician any hints as to what’s up.

Transmission problems with this make and model are hardly unknown, so avoid driving the vehicle any farther until it’s been looked at. You may end up doing more damage by continuing to drive it.

The actual problem could be anything from a transmission that is about to catastrophically fail, to one that has simply lost its 'memory' or programming and can be rebooted fairly easily and quickly.

Conventional wisdom says the first place to start looking is the turbocharger and its plumbing. A turbocharger operates at very high speeds and a whistling noise is quite common. What you shouldn’t have, however, is a loud version of that noise, or a whistle that is suddenly louder than ever before.

Cracked or leaking turbo-plumbing can allow the noise to escape, but a turbocharger with a worn bearing can also suddenly become louder in its operation. So that’s where to start looking.

Why does the noise drop in the higher gears? Perhaps because you’re cruising in those gears and not accelerating hard as you do in the lower gears. Less throttle input means a slower turbocharger speed and a drop in turbo volume and pitch.