Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the part of the car that helps change electricity from one type to another is taking too long to turn off. It's like a toy that keeps spinning even after you stop pushing it.
The DC/DC converter in a vehicle is responsible for converting high voltage from the battery to lower voltages needed by other systems. This code indicates that the discharge time of the internal DC link capacitor is longer than expected.
The DC/DC converter's internal DC link capacitor is supposed to discharge its stored energy within a specific time frame. If the discharge process takes too long, it may indicate a malfunction in the converter's circuitry or a fault in the capacitor itself.
• Warning light on the dashboard
• Reduced vehicle performance
• Electrical system malfunctions
• Faulty DC/DC converter
• Wiring issues
• Faulty capacitor
DC/DC Converter: A device that converts direct current (DC) from one voltage level to another.
Capacitor: An electronic component that stores and releases electrical energy.
• Use a diagnostic scanner to confirm the code.
• Inspect the DC/DC converter and its wiring.
• Test the capacitor discharge time.
• Replace the DC/DC converter if faulty.
• Repair or replace any damaged wiring.
• Replace the capacitor if it is defective.
• Diagnostic scanner
• Multimeter
• Screwdriver set
$300 - $800
Moderate
• Chevrolet Volt
• Toyota Prius
• Nissan Leaf
• Regular maintenance checks
• Ensure proper electrical connections
• Avoid overloading the electrical system
Electrical System Issue
• Seek professional help if unsure.
• Do not ignore the warning light.
• Avoid using high electrical loads until fixed.
Check with the vehicle manufacturer for warranty coverage on electrical components.
This code has been reported in hybrid and electric vehicles due to their complex electrical systems.
Moderate – It should be addressed soon to avoid further electrical issues.
Ignoring electrical faults can lead to safety hazards. Always consult a professional for repairs.
• Vehicle in park with ignition on
• Ensure battery is fully charged
The DC/DC converter is typically located near the vehicle's battery or under the hood.
Q: Can I drive with code P1A91?
A: It's not recommended to drive for long distances as it may lead to further electrical issues.
Q: How do I reset the code?
A: After repairs, use a diagnostic scanner to clear the code.
Budget · Enhanced code reader
A wired color-screen reader with readiness hotkeys, live data, code definitions, and data logging.
A dependable first-pass scanner for verifying the code and checking live data or readiness monitors.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for voltage, continuity, and basic electrical checks while narrowing down the fault.
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Universal · Socket set
A practical metric and SAE socket set for many diagnostic teardowns and component replacements.
Useful for common under-hood access and removal work during diagnosis or repair.
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