Metering Oil Pump Position Sensor Circuit (Mazda)
What does P1681 mean?
The P1681 code means the vehicle's onboard diagnostic system has detected: Metering Oil Pump Position Sensor Circuit (Mazda). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Incorrect oil metering rate
- Excessive oil consumption
- Blue exhaust smoke
- Engine running rough at high RPM
Probable Causes (Ranked by Likelihood)
- Faulty metering oil pump position sensor Very High
- Corroded sensor connector or wiring High
- Oil contamination on sensor Moderate
- ECU sensor input circuit malfunction Low
Step-by-Step Diagnostic Procedure
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Access the metering oil pump position sensor on the oil pump assembly.
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Inspect the sensor connector for oil contamination, corrosion, or damage.
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Measure sensor output voltage while varying pump position (should provide a smooth voltage change).
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Check for 5V reference and ground at the sensor connector.
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If the sensor is faulty, replace it and verify proper oil metering rates with a scan tool.
Frequently Asked Questions
What does the metering oil pump position sensor do?
It monitors the metering oil pump output to ensure the correct amount of oil is being injected into the rotary engine combustion chambers.
Can incorrect oil metering damage the engine?
Yes. Too little oil causes apex seal wear and housing scoring. Too much oil causes fouled spark plugs and excessive carbon buildup.
Is this a common failure on the RX-8?
The sensor itself is not a frequent failure, but oil contamination of the connector is common. Cleaning the connector often resolves the issue.