MX-5 Miata L4-2.0L (2008)
1-10 ohms
Front HO2S Circuit Open/Short Inspection
1. Disconnect the PCM connector.
2. Disconnect the front HO2S connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)
Open circuit
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If there is no continuity in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness.
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Front H02S terminal A and PCM terminal 2AD
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Front H02S terminal B and PCM terminal 2Z
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Front H02S terminal C ignition relay
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Front H02S terminal D and PCM terminal 2BG
Short circuit
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If there is continuity in the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
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Front H02S terminal A and power supply
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Front H02S terminal A and body ground
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Front H02S terminal B and power supply
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Front HO2S terminal B and body ground
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Front H02S terminal C and body ground
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Front H02S terminal D and power supply
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Front H02S terminal D and body ground
Rear Heated Oxygen Sensor (HO2S) Inspection
REAR HEATED OXYGEN SENSOR (HO2S) INSPECTION [LF]
NOTE: Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart. (See HOW TO
USE THIS MANUAL.)
Rear HO2S Voltage Inspection
1. Warm up the engine to normal operating temperature.
2. Using the M-MDS, monitor the following:
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Vehicle speed (PID: VSS)
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Engine speed (PID: RPM)
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Rear HO2S voltage (PID: O2S12)
3. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 rpm or more.
4. Verify that the rear HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the rear HO2S voltage (PID: O2S12) is 0.3 V or
less while decelerating as shown in the figure.