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.

2013 Mazda MX-5 Miata Grand Touring, Automatic TransFACTORY OEM SERVICE PROCEDURE

HO2S Circuit Open/Short Inspection

Fig 1: Identifying HO2S Wiring Harness-Side Connector Terminals

Courtesy of MAZDA MOTORS CORP.

Disconnect the PCM connector.
Disconnect the HO2S connector.
Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

Fig 2: Identifying PCM Wiring Harness-Side Connector Terminals
Courtesy of MAZDA MOTORS CORP.

Open circuit

If there is no continuity, there is an open circuit. Repair or replace the wiring harness.
- HO2S terminal A and PCM terminal 2Q
- HO2S terminal B and PCM terminal 2BH
- HO2S terminal C and ignition relay
- HO2S terminal D and PCM terminal 2BE

Short circuit

If there is continuity in the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
- HO2S terminal A and power supply
- HO2S terminal A and body ground
- HO2S terminal B and power supply
- HO2S terminal B and body ground
- HO2S terminal C and body ground
- HO2S terminal D and power supply
- HO2S terminal D and body ground

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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