P1686 Code: Meaning, Symptoms, Causes & Fix

Overview

Symptoms

• reduced performance
• increased fuel use
• check engine light

Common causes

• Open circuit in wiring affecting metering oil pump stepping motor circuit malfunction
• Broken terminal inside harness
• Connector pin damage/corrosion or harness stress near related components

How to diagnose P1686

1. Confirm P1686 and capture freeze-frame data with a professional scan tool.
2. Inspect wiring, connectors, and grounds related to metering oil pump stepping motor circuit malfunction for obvious defects.
3. Use a continuity test from module pin to component to identify opens/high resistance.
4. Check for related DTCs to identify the root-cause chain before replacing parts.
5. After repair, clear codes and confirm readiness monitors complete without recurrence.

Severity of code P1686

Moderate: This code is moderate severity: the vehicle may still operate, but fault progression can increase repair cost over time.

Can you drive with P1686?

Most vehicles can be driven short-term with P1686, but postpone heavy load/highway driving until repaired.

If the warning lamp is flashing or drivability/safety is affected, avoid driving and diagnose immediately.

How to fix it (step-by-step)

1. Repair obvious wiring/connector faults first to prevent repeat parts replacement.
2. Address the root fault mode (open) in the metering oil pump stepping motor circuit malfunction circuit/system.
3. Apply the required relearn/adaptation procedure if specified by service information.
4. Road-test and verify P1686 remains cleared under the conditions that originally set the code.

Fix options

• Repair open circuit and secure connector lock.
• Clear corrosion and protect terminals.
• Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$200-$900

Common mistakes when diagnosing P1686

• Replacing parts without verifying voltage, ground, and signal integrity first.
• Ignoring related stored/pending codes that indicate upstream faults.
• Skipping post-repair verification drive cycle and readiness checks.

P1686 in common vehicles

P1686 appears across makes such as Mazda, Subaru, Lexus, Jeep. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes P1686?

P1686 is commonly set by open faults affecting metering oil pump stepping motor circuit malfunction.

How much does it cost to fix P1686?

For P1686, repair costs are typically $200-$900 depending on exact root cause, labor rates, and part quality.

Can I clear P1686 without repair?

You can clear P1686 temporarily, but the code usually returns until the underlying fault is corrected.

Helpful tools

• Estimate repair cost
• Decode your VIN
• Calculate fuel cost