MX-5 Miata Mazdaspeed L4-1.8L DOHC Turbo (2004)
NOTE: Perform the following test only when directed.
1. Warm up the engine and idle it.
2. Disconnect the HO2S connector.
3. Connect a voltmeter between the HO2S connector terminal A and a GND.
4. Run the engine at 3,000 rpm until the voltmeter indicates 0 - 1.0 V.
5. Verify the voltage when engine speed is suddenly increased and decreased several times.
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If HO2S is okay, but PID value is out of specification, perform the "Circuit Open/Short Inspection".
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If not as specified, replace the HO2S.
6. Reconnect the HO2S connector.
Circuit Open/Short Inspection
Open circuit
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If there is no continuity, the circuit is open. Repair or replace the harness.
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Heated oxygen circuit (HO2S connector terminal A and PCM connector terminal 4W (Front).)
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GND circuit (HO2S connector terminal B and PCM connector terminal 4O through common connector (Front).)
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Heated oxygen circuit (HO2S connector terminal A and PCM connector terminal 4AA (Rear).)
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GND circuit (HO2S connector terminal B and PCM connector terminal 4O through common connector (Rear).)
Short circuit
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If there is continuity, the circuit is shorted. Repair or replace the harness.
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HO2S connector terminal A and PCM connector terminal 4W to GND (Front).
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HO2S connector terminal A and PCM connector terminal 4AA to GND (Rear).
