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: Camshaft position (cmp) sensor inspection
Caution When foreign material such as an iron chip is on the CMP sensor, it can cause abnormal output from the sensor because of flux turbulence and adversely affect the engine control. Be sure there is no foreign material on the CMP sensor when replacing. Note Perform the follow ...

Mazda 6 Service Manual: Engine coolant temperature (ect) sensor inspection
Note Perform the following inspection only when directed. ECT Sensor Resistance Inspection 1. Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS.) 2. Remove the ECT sensor (located above the starter). 3. Place the ECT sensor in water with a thermometer, and heat the water gra ...