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 RX8 2RTR-1.3LFACTORY OEM SERVICE PROCEDURE
Engine Temperature Sensor: Testing and Inspection
ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION
NOTE: Before performing the following inspection, make sure to follow the troubleshooting flowchart. (See FOREWORD.) Flow of Diagnosis
Resistance Inspection
1. Disconnect the ECT sensor connector.
2. Remove the ECT sensor.
3. Place the detection part of the ECT sensor in water and verify that the resistance between ECT sensor terminals A and B is as indicated in the table while gradually increasing water temperature.
- If the monitor item condition/specification (reference) is not within the specification, even though the resistance is within the specification, perform the "Circuit Open/Short Inspection".
- If not within the specification, replace the ECT sensor.
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Disconnect the ECT sensor connector.
3. Inspect the following wiring harnesses for open or short circuit. (Continuity inspection)
Open circuit
- If there is no continuity in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness.
- ECT sensor terminal A and PCM terminal 2K
- ECT sensor terminal B and PCM terminal 1U
Short circuit
- If there is continuity at the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
- ECT sensor terminal A and body ground
- ECT sensor terminal A and power supply
NOTE: Before performing the following inspection, make sure to follow the troubleshooting flowchart. (See FOREWORD.) Flow of Diagnosis
Resistance Inspection
1. Disconnect the ECT sensor connector.
2. Remove the ECT sensor.
ECT Sensor Characteristics Graph (Reference):
3. Place the detection part of the ECT sensor in water and verify that the resistance between ECT sensor terminals A and B is as indicated in the table while gradually increasing water temperature.
- If the monitor item condition/specification (reference) is not within the specification, even though the resistance is within the specification, perform the "Circuit Open/Short Inspection".
- If not within the specification, replace the ECT sensor.
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Disconnect the ECT sensor connector.
3. Inspect the following wiring harnesses for open or short circuit. (Continuity inspection)
Open circuit
- If there is no continuity in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness.
- ECT sensor terminal A and PCM terminal 2K
- ECT sensor terminal B and PCM terminal 1U
Short circuit
- If there is continuity at the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
- ECT sensor terminal A and body ground
- ECT sensor terminal A and power supply
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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