1. If not as specified, loosen the fuel-filler lid installation bolts, and reposition the fuel-filler lid.
2. Measure the gap and height between the fuel-filler lid and the body.
Clearance
a: 1.7-3.7 mm {0.067-0.145 in} b: -0.5-1.5 mm {-0.019-0.059 in}
3. Tighten the bolts.

Fuel-filler lid and opener removal/installation
BumperMazda 6 Service Manual: Mazda Radar Cruise Control (MRCC) (Some models)
The Mazda Radar Cruise Control (MRCC) system is designed to maintain headway
control*1 according to the vehicle speed using a radar sensor (front) to detect
the distance to a vehicle ahead, and by presetting the vehicle speed between 30
km/h (19 mph) and 145 km/h (90 mph), the driver is freed ...
Mazda 6 Service Manual: Intermittent concern troubleshooting
Vibration Method
1. If malfunction occurs or becomes worse while driving on a rough road or
when engine is vibrating, perform the steps below.
Note
There are several reasons vehicle or engine vibration could cause
an electrical malfunction. Some of the things to check for are:
...