P1691 Oil Metering Pump Stepper Motor Circuit
The P1691 code indicates that the ECU has detected an electrical fault in the stepper motor circuit of the metering oil pump. This pump is part of the MIVEC variable valve timing system and regulates oil pressure to control camshaft timing. The fault could be an open circuit, short to ground, short to battery, or internal failure of the stepper motor, preventing the ECU from properly modulating hydraulic pressure.
01. Most Common Causes
- Faulty metering oil pump stepper motor (open or shorted coils)
- Damaged wiring or connectors between ECU and pump (short, open, corrosion)
- Blown fuse in the pump power circuit
- Internal ECU failure (damaged stepper motor driver)
- Incorrect engine oil level or pressure affecting mechanical feedback
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or power loss
- Rough idle or stalling
- Poor fuel economy
- Possible limp mode activation
03. Step-by-Step Diagnosis
Scan for additional codes and freeze frame data
Visually inspect wiring and connectors for damage or corrosion
Test the stepper motor resistance and continuity per manufacturer specs
Check the fuse for the oil pump circuit
Verify engine oil level and condition
If all else passes, test ECU output signals or replace ECU
1. Frequently Asked Questions
Is it safe to drive?▼
No, it is not safe to drive. The fault can cause improper valve timing, leading to reduced engine performance, potential stalling, and possible engine damage if driven for extended periods.
How much does it cost to fix?▼
Repair costs typically range from $200 to $800, depending on the root cause. A stepper motor replacement may cost $150-$400, wiring repairs $100-$300, and ECU replacement $500-$1000.