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P1684 — Metering Oil Pump Position Sensor Circuit Malfunction

Manufacturer-specificPowertrain (engine & transmission)

This code indicates the engine control module has detected an electrical irregularity within the circuit monitoring the metering oil pump position. The metering oil pump is responsible for injecting lubricating oil into the engine intake or fuel system to maintain internal lubrication. When this circuit malfunctions, the system cannot verify proper oil delivery rates or pump positioning.

Symptoms

What causes it — most likely first

1. Failed position sensor

Internal electrical failure within the sensor prevents accurate position reporting to the control module.

2. Damaged wiring harness

Heat or oil exposure near the pump causes shorts or open circuits in the wiring connecting the sensor.

3. Pump mechanical binding

Physical obstruction or wear prevents the pump from moving to the commanded position.

4. Blown fuse or relay

Power supply interruption stops the pump circuit from functioning correctly.

5. Poor ground connection

Corrosion or looseness at the ground point disrupts sensor voltage signals.

6. Faulty control module

Internal processor error is rare and should only be considered after all other components are verified.

How it's diagnosed

  1. Inspect the metering oil pump reservoir level and refill if low.
  2. Visually examine wiring harness and connectors for oil saturation or damage.
  3. Test sensor resistance and voltage reference signals against specifications.
  4. Check power and ground supply to the metering oil pump assembly.
  5. Verify mechanical operation of the pump motor and linkage manually.
  6. Rule out wiring and component faults before considering module replacement.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)

Frequently asked

Is it safe to drive with this code?

No, continued driving risks severe engine damage due to insufficient internal lubrication.

Does this code mean I need a new computer?

No, PCM failure is rare and the sensor or wiring is the usual cause.

Will resetting the code fix the problem?

No, the underlying electrical or mechanical fault will cause the code to return.

Can low oil cause this code?

Yes, an empty reservoir can prevent the pump from operating within expected parameters.