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.
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HOMESERVICE MANUALSMAZDA2009CX-9 FWD V6-3.7LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMKNOCK SENSORTESTING AND INSPECTION
2009 Mazda CX-9 FWD V6-3.7L
Knock Sensor: Testing and Inspection
2009 Mazda CX-9 FWD V6-3.7LSECTION Testing and Inspection
KNOCK SENSOR (KS) INSPECTION [MZI-3.7]
NOTE:
- Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart. Description and Operation
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 Mohms
Circuit Open/Short Inspection
1. Disconnect the PCM connector. Service and Repair
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 2Q
- 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
RENDER: 1.0x
NO RELATED
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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.