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
Knock Sensor: Testing and Inspection
KNOCK SENSOR (KS) INSPECTION
Resistance Inspection
NOTE: Before performing the following inspection, make sure to follow the troubleshooting flowchart. (See FOREWORD.) Flow of Diagnosis
1. Disconnect the KS connector.
2. Measure the resistance between KS terminals A and B.
- If not within the specification, replace the KS.
- If the monitor item condition/specification (reference) is not within the specification, even though the KS resistance is within the specification, perform the "Circuit Open/Short Inspection".
KS resistance: 120 - 280 kOhms
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Disconnect the KS connector.
3. Inspect the following wiring harnesses for open or short. (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.
- KS terminal A and PCM terminal 1T
- KS terminal B and PCM terminal 1F
Short circuit
- If there is continuity in the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
- KS terminal A and body ground
- KS terminal A and power supply
- KS terminal B and body ground
- KS terminal B and power supply
Resistance Inspection
NOTE: Before performing the following inspection, make sure to follow the troubleshooting flowchart. (See FOREWORD.) Flow of Diagnosis
1. Disconnect the KS connector.
2. Measure the resistance between KS terminals A and B.
- If not within the specification, replace the KS.
- If the monitor item condition/specification (reference) is not within the specification, even though the KS resistance is within the specification, perform the "Circuit Open/Short Inspection".
KS resistance: 120 - 280 kOhms
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Disconnect the KS connector.
3. Inspect the following wiring harnesses for open or short. (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.
- KS terminal A and PCM terminal 1T
- KS terminal B and PCM terminal 1F
Short circuit
- If there is continuity in the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
- KS terminal A and body ground
- KS terminal A and power supply
- KS terminal B and body ground
- KS terminal B 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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