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.

2004 Mazda MX-5 Miata Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Inspection Of Resistance

NOTE:

Perform the following test only when directed.

Drain the engine coolant. See COOLING SYSTEM SERVICE WARNINGS and ENGINE COOLANT REPLACEMENT .
Disconnect the ECT sensor connector.
Remove the ECT sensor.

Fig 1: Identifying Engine Coolant Temperature Sensor Connector
Courtesy of MAZDA MOTORS CORP.
Place the sensor in water with a thermometer, and heat the water gradually.

Fig 2: Testing Engine Coolant Temperature Sensor
Courtesy of MAZDA MOTORS CORP.
Measure the resistance between the ECT sensor terminals using an ohmmeter.
- If not as specified, replace the ECT sensor.
- If ECT sensor is okay, but PID value is out of specification, perform the "Circuit Open/Short Inspection". See CIRCUIT OPEN/SHORT INSPECTION .
Specification

Fig 3: Engine Coolant Temperature Sensor Resistance Specifications (1 Of 2)
Courtesy of MAZDA MOTORS CORP.

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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