Metering Oil Pump Stepping Motor Circuit Malfunction
The engine's metering oil pump stepper motor isn't responding correctly to commands from the ECU. Think of it like a dimmer switch that won't adjust properly—the pump can't fine-tune oil flow to the variable valve timing system.
The ECU commands the metering oil pump stepper motor to adjust oil pressure for variable valve timing optimization. It monitors electrical continuity, coil resistance, and motor response times to detect circuit faults, open circuits, or shorts.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Motor Coil Resistance | 3-8 ohms per coil | Open circuit or >15 ohms |
| Motor Response Time | <100ms per step | >200ms or no response |
Code P1690 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1690 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.