MX-5 Miata L4-2.0L (2008)
Oxygen Sensor: Component Tests and General Diagnostics
Front Heated Oxygen Sensor (HO2S) Inspection
FRONT 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.)
Front HO2S Current 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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Front HO2S current (PID: O2S11)
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 front HO2S current (PID: O2S11) is 0.25 mA more or while decelerating as shown in the figure.
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If not within the specification, inspect the front HO2S for an open or short circuit. (See FRONT HEATED OXYGEN SENSOR (H025)
INSPECTION [LF].) Then if there is no malfunction in the wiring harness, replace the front HO2S.
Front HO2S Heater Resistance Inspection
1. Disconnect the front HO2S connector.
2. Measure the resistance between front HO2S terminals C and D.
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If not within the specification, replace the front HO2S.
Front HO2S heater resistance
