MX-5 Miata L4-1.8L DOHC (1996)
Oxygen Sensor: Testing and Inspection
HO2S Inspection Procedures
SENSOR INSPECTION
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Warm up the engine to normal operating temperature.
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Connect the SSTs (Engine Signal Monitor) to the ECM.
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Measure the ECM terminal 3C and 3D voltages.
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If not as specified, inspect the following:
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Harness and connector between heated oxygen sensor and ECM.
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On-board diagnostic system
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Intake manifold vacuum
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Fuel line pressure
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If all the systems are OK, replace the heated oxygen sensor.
USING THE NGS
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Connect the SSTs (NGS) to the data link connector-2.
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Select the PID/DATA MONITOR AND RECORD function of the NGS.
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Select "FHO2S", "RHO2S" on the NGS display. The NGS measures and shows the voltage.
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If not as specified, inspect the following:
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Harness and connector between heated oxygen sensor and ECM.
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On-board diagnostic system
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Intake manifold vacuum
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Fuel line pressure
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If all the systems are OK, replace the heated oxygen sensor.
HEATER
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Disconnect the heated oxygen sensor connector.
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Measure the resistance between heated oxygen sensor terminals D and C by using an ohmmeter.
