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.
2007 Mazda CX-9 V6-3.5LFACTORY OEM SERVICE PROCEDURE
Knock Sensor: Testing and Inspection
KNOCK SENSOR (KS) INSPECTION [MZI-3.5]
NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.
Resistance Inspection
1. Turn the ignition switch to LOCK.
2. Disconnect the KS connector.
3. Measure the resistance between the KS terminals.
KS(RH): KS terminals A and B
KS(LH): KS terminals C and D
- If not as specified, replace the KS.
- If the KS is normal, but PID value is out of specification, perform the "Circuit Open/Short Inspection".
KS resistance: 4.39-5.35 ohms
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for open or short. (Continuity inspection)
Open circuit
- If there is no continuity, the circuit is open. Repair or replace the wiring harness.
- KS terminal A and PCM terminal 20
- KS terminal B and PCM terminal 2M
- KS terminal C and PCM terminal 2L
- KS terminal D and PCM terminal 2G
Short circuit
- If there is continuity, the circuit is shorted. Repair or replace the wiring harness.
- KS terminal A and power supply
- KS terminal A and body ground
- KS terminal B and power supply
- KS terminal B and body ground
- KS terminal C and power supply
- KS terminal C and body ground
- KS terminal D and power supply
- KS terminal D and body ground
NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.
Resistance Inspection
1. Turn the ignition switch to LOCK.
2. Disconnect the KS connector.
3. Measure the resistance between the KS terminals.
KS(RH): KS terminals A and B
KS(LH): KS terminals C and D
- If not as specified, replace the KS.
- If the KS is normal, but PID value is out of specification, perform the "Circuit Open/Short Inspection".
KS resistance: 4.39-5.35 ohms
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for open or short. (Continuity inspection)
Open circuit
- If there is no continuity, the circuit is open. Repair or replace the wiring harness.
- KS terminal A and PCM terminal 20
- KS terminal B and PCM terminal 2M
- KS terminal C and PCM terminal 2L
- KS terminal D and PCM terminal 2G
Short circuit
- If there is continuity, the circuit is shorted. Repair or replace the wiring harness.
- KS terminal A and power supply
- KS terminal A and body ground
- KS terminal B and power supply
- KS terminal B and body ground
- KS terminal C and power supply
- KS terminal C and body ground
- KS terminal D and power supply
- KS 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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