Mazda 6 Service Manual: No.20 fuel odor (in engine compartment)

No.19 exhaust smoke

No.21 engine noise

Other materials:

Mazda 6 Service Manual: Underbody Maintenance
Road chemicals and salt used for ice and snow removal and solvents used for dust control may collect on the underbody. If not removed, they will speed up rusting and deterioration of such underbody parts as fuel lines, frame, floor pan, and exhaust system, even though these parts may be coated ...

Mazda 6 Service Manual: Immobilizer System
The immobilizer system allows the engine to start only with a key the system recognizes. If someone attempts to start the engine with an unrecognized key, the engine will not start, thereby helping to prevent vehicle theft. If you have a problem with the immobilizer system or the key, consult ...