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.
2005 Mazda 6 L4-2.3LFACTORY OEM SERVICE PROCEDURE
Knock Sensor: Testing and Inspection
KNOCK SENSOR (KS) INSPECTION
NOTE: Perform the following test only when directed.
Resistance Inspection
1. Turn the ignition switch to LOCK.
2. Disconnect the KS connector.
3. Measure the resistance between the KS terminals A and B using an ohmmeter.
- 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".
Specification
Approx. 4.87 megohms
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for open or short circuit. (Continuity check)
Open circuit
- If there is no continuity, there is an open circuit. Repair or replace the wiring harness.
- KS terminal A and PCM terminal 81*1, 2S*2
- KS terminal B and PCM terminal 3*1, 2P*2
Short circuit
- If there is continuity, there is a short circuit. Repair or replace the wiring harness.
- KS terminal A and power supply
- KS terminal A and body GND
- KS terminal B and power supply
- KS terminal B and body GND
*1 : California emission regulation applicable ATX model
*2 : Except for California emission regulation applicable ATX model
NOTE: Perform the following test only when directed.
Resistance Inspection
1. Turn the ignition switch to LOCK.
2. Disconnect the KS connector.
3. Measure the resistance between the KS terminals A and B using an ohmmeter.
- 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".
Specification
Approx. 4.87 megohms
Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for open or short circuit. (Continuity check)
Open circuit
- If there is no continuity, there is an open circuit. Repair or replace the wiring harness.
- KS terminal A and PCM terminal 81*1, 2S*2
- KS terminal B and PCM terminal 3*1, 2P*2
Short circuit
- If there is continuity, there is a short circuit. Repair or replace the wiring harness.
- KS terminal A and power supply
- KS terminal A and body GND
- KS terminal B and power supply
- KS terminal B and body GND
*1 : California emission regulation applicable ATX model
*2 : Except for California emission regulation applicable ATX model
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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