What Does P1691 Mean?
Another variant of metering oil pump stepping motor circuit malfunction specific to rotary engines. This may indicate a different monitoring strategy or additional circuit failure beyond codes P1685-P1687.
Common Causes
35%
Metering oil pump stepping motor electrical failure
25%
ECM driver circuit malfunction for MOP control
25%
Wiring harness chafing or connector corrosion
10%
Power supply interruption to MOP motor circuit
5%
Internal MOP mechanical failure preventing motor operation
Diagnostic Steps
1
Step 1: Perform voltage drop test on power and ground circuits to MOP motor (should be less than 0.5V)
2
Step 2: Check all stepping motor phase resistances and compare to specifications
3
Step 3: Monitor ECM commanded vs actual MOP position during engine operation
4
Step 4: Inspect for oil leaks at MOP that could indicate internal mechanical failure
5
Step 5: Test ECM outputs with MOP disconnected to verify driver circuit functionality
Estimated Repair Cost
$300 - $1,200
Parts + labor, varies by vehicle and location
Another variant of metering oil pump stepping motor circuit malfunction specific to rotary engines. This may indicate a different monitoring strategy or additional circuit failure beyond codes P1685-P1687.
The most common cause of P1691 (Metering Oil Pump Stepping Motor Circuit Malfunction) is: Metering oil pump stepping motor electrical failure
Typical repair costs for P1691 range from $300 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Inadequate oil injection will rapidly damage rotary engine apex seals and housings. Limit driving to emergency situations only.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1691 to identify the root cause.
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Quick Info
Category
Powertrain
System
Rotary Engine Lubrication System
Difficulty
Type
Manufacturer
Recommended Tools
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