
Diagnostic Procedure

Dtc 18
Dtc 21Mazda 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 ...
Mazda 6 Service Manual: Schedule 2
U.S.A. and Puerto Rico residents - Severe driving conditions maintenance interval
Chart symbols:
I: Inspect: Inspect and clean, repair, adjust, fill up, or replace if
necessary.
R: Replace
L: Lubricate
T: Tighten
Remarks:
*1 Engine oil flexible maintenance is available for U.S.A. and Pu ...