Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

2021 Mazda 3 BaseFACTORY OEM SERVICE PROCEDURE

HS/Ms Can System DTCS

HS/MS CAN SYSTEM DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION

DTC output module	Reference for initial letter of DTC
PCM	(See DTC TABLE [PCM (VINs 7, L, M) (US)] .) (See DTC TABLE [PCM ((VIN Y))] .)












DSC HU/CM	(See DTC TABLE [DSC HU/CM (US)] .)











EPS control module	(See DTC TABLE [ELECTRIC POWER STEERING (EPS) (US)] .)




Vehicle control module (VCM)	(See DTC TABLE [VEHICLE CONTROL MODULE (US)] .)































Body control module (BCM)	(See DTC TABLE [BODY CONTROL MODULE (BCM) (US)] .)





































Connectivity master unit (CMU)	(Refer to the DTC TABLE [CONNECTIVITY MASTER UNIT (US)] in the service information)
Connectivity master unit (CMU)
Telematics communication unit	(See DTC TABLE [TELEMATICS COMMUNICATION UNIT] .)






Adaptive front lighting system (AFS) control module	(See DTC TABLE [ADAPTIVE FRONT LIGHTING SYSTEM (AFS) CONTROL MODULE (US)] .)





Dash-electrical supply unit	(See DTC TABLE [DASH-ELECTRICAL SUPPLY UNIT (US)] .)









SAS control module	(See DTC TABLE [SAS CONTROL MODULE (TWO-STEP DEPLOYMENT CONTROL SYSTEM - US/CANADA SPEC.)] .)



TCM	(See ON-BOARD DIAGNOSTIC SYSTEM DTC TABLE [TCM (ET6A-EL ) (US)] .) (See ON-BOARD DIAGNOSTIC SYSTEM DTC TABLE [TCM (EV6A-EL, EV6AX-EL) (US)] .) (See ON-BOARD DIAGNOSTIC SYSTEM DTC TABLE [TCM (GW6AX-EL) (US)] .)

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.

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