Mazda 6 Service Manual: No.3 will not crank

No.2 mil illuminates

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

Other materials:

Mazda 6 Service Manual: Immobilizer system reprogram procedure
Note When an error occurs during the reprogram procedures, except when the PCM is replaced, repeat the procedure from Step 1. If you still cannot reprogram, confirm how many keys can start the engine. Then, perform the key replacement or addition reprogram procedure according to the val ...

Mazda 6 Service Manual: Heater core inspection
1. Remove the A/C unit. (See A/C UNIT REMOVAL/INSTALLATION.) 2. Remove the heater core from the A/C unit. 3. Inspect for cracks, damage, and coolant leakage. If any problems are found, replace the heater core. 4. Inspect for bent fins. If any are bent, use a flathead screwdriver to stra ...