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 MANUALSMAZDA1991MX-6 L4-2184CC 2.2L SOHC TURBO F2REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMKNOCK SENSORTESTING AND INSPECTION
1991 Mazda MX-6 L4-2184cc 2.2L SOHC Turbo F2
Knock Sensor: Testing and Inspection
1991 Mazda MX-6 L4-2184cc 2.2L SOHC Turbo F2SECTION Testing and Inspection
MALFUNCTION CODE
If the engine "pings" excessively and base timing is okay, check the on-board diagnostic system. A faulty knock sensor or knock control unit will set malfunction code 05. Refer to DIAGNOSTIC CHARTS.
KNOCK CONTROL SYSTEM TEST
1. Connect Mazda Self-Diagnosis Checker (SST #49 H018 9A1) or equivalent aftermarket "Scan" tool to check connector.
2. Ground test connector with a jumper wire.
3. Turn ignition switch "ON."
4. Tap right engine hanger (drive belt side) with hammer and check that SST monitor lamp flashes.
5. If lamp does not flash, connect a known good knock sensor to wiring harness and provide sensor with a good ground.
6. Repeat tapping procedure. If lamp now flashes, original sensor is defective and should be replaced.
7. If lamp still does not flash, knock control unit may be defective. Ensure that wiring and harness connections are in good condition before replacing control unit.
Knock control unit input voltage can be checked at ECU terminal 2M. With ignition "ON" and engine running at idle, voltage should be 3.3 - 5.0V. When knocking occurs, voltage should be 1.3 - 2.6V.
If the engine "pings" excessively and base timing is okay, check the on-board diagnostic system. A faulty knock sensor or knock control unit will set malfunction code 05. Refer to DIAGNOSTIC CHARTS.
KNOCK CONTROL SYSTEM TEST
Knock Control System Testing:
1. Connect Mazda Self-Diagnosis Checker (SST #49 H018 9A1) or equivalent aftermarket "Scan" tool to check connector.
2. Ground test connector with a jumper wire.
3. Turn ignition switch "ON."
4. Tap right engine hanger (drive belt side) with hammer and check that SST monitor lamp flashes.
5. If lamp does not flash, connect a known good knock sensor to wiring harness and provide sensor with a good ground.
6. Repeat tapping procedure. If lamp now flashes, original sensor is defective and should be replaced.
7. If lamp still does not flash, knock control unit may be defective. Ensure that wiring and harness connections are in good condition before replacing control unit.
Knock control unit input voltage can be checked at ECU terminal 2M. With ignition "ON" and engine running at idle, voltage should be 3.3 - 5.0V. When knocking occurs, voltage should be 1.3 - 2.6V.
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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.