What Does P1686 Mean?
A secondary or redundant detection of a metering oil pump stepping motor circuit malfunction. This code indicates a fault in a different phase or monitoring circuit of the MOP stepping motor on rotary engines.
Common Causes
35%
Faulty metering oil pump stepping motor (different phase than P1685)
30%
Open or short circuit in MOP motor control wiring
20%
ECM internal driver circuit for alternate phase failure
10%
Intermittent connection at MOP connector terminals
5%
Voltage supply issue to MOP motor
Diagnostic Steps
1
Step 1: Perform continuity test on all four stepping motor phase wires from ECM connector to MOP motor
2
Step 2: Measure resistance between each phase winding (should be balanced within 5 ohms)
3
Step 3: Check for voltage supply to MOP motor (typically 12V constant)
4
Step 4: Inspect connector terminals for bent pins, corrosion, or loose fit
5
Step 5: Compare ECM commanded step position with actual motor movement using oscilloscope if available
Estimated Repair Cost
$300 - $1,200
Parts + labor, varies by vehicle and location
A secondary or redundant detection of a metering oil pump stepping motor circuit malfunction. This code indicates a fault in a different phase or monitoring circuit of the MOP stepping motor on rotary engines.
The most common cause of P1686 (Metering Oil Pump Stepping Motor Circuit Malfunction) is: Faulty metering oil pump stepping motor (different phase than P1685)
Typical repair costs for P1686 range from $300 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of proper oil metering leads to inadequate apex seal lubrication and rapid engine wear. Minimize driving until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1686 to identify the root cause.
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Quick Info
Category
Powertrain
System
Rotary Engine Lubrication System
Difficulty
Type
Manufacturer
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