Mazda 6 Service Manual: No.5 engine stalls-after start/at idle

No.4 hard to start/long crank/erratic start/erratic crank

No.6 cranks normally but will not start

Other materials:

Mazda 6 Service Manual: Radar Sensors (Rear) (Some models)
Your vehicle is equipped with radar sensors (rear). The following systems also use the radar sensors (rear). Blind Spot Monitoring system (BSM) Rear Cross Traffic Alert (RCTA) The radar sensors (rear) function by detecting the radio waves reflected off a vehicle approaching from the rea ...

Mazda 6 Service Manual: Dual proportioning valve inspection (without abs)
1. Connect the SSTs to the brake pipes as shown in the figure. 2. Bleed the air from the brake system. 3. Measure the fluid pressure of the master cylinder and the rear brake. If not within the specification, replace the dual proportioning valve. Fluid pressure ...