Engine-CodesGeneric – P0999

P0999 Code - Shift Solenoid 'F' Control Circuit High

Quick Answer

The P0999 code indicates a problem with the Shift Solenoid 'F' Control Circuit in the vehicle's transmission system. Common causes include Faulty Shift Solenoid 'F', Wiring issues or shorts in the control circuit, Corrosion or poor connections in the electrical system. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0999 indicates Shift Solenoid 'F' Control Circuit High.
Common causes
Common causes include Faulty Shift Solenoid 'F', Wiring issues or shorts in the control circuit, Corrosion or poor connections in the electrical system.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Table of contents Created and updated by William Orellana on Sep 09, 2024
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Code P0999 Description

The P0999 code indicates a problem with the Shift Solenoid 'F' Control Circuit in the vehicle's transmission system. The shift solenoid is responsible for controlling the flow of transmission fluid, which in turn controls the shifting of gears in the transmission. When the control circuit for Shift Solenoid 'F' is detected to be operating at a higher than normal voltage, it signifies an issue with the solenoid's electrical circuit.

OBDII Code P0999 - Shift Solenoid 'F' Control Circuit High
P0999 Code - Shift Solenoid 'F' Control Circuit High

Common Causes of P0999

  1. Faulty Shift Solenoid 'F'
  2. Wiring issues or shorts in the control circuit
  3. Corrosion or poor connections in the electrical system
  4. Low transmission fluid levels
  5. Engine control module (ECM) failure

Symptoms of P0999

  1. Harsh or delayed shifting of gears
  2. Inability to shift gears
  3. Limp mode operation
  4. Illumination of the check engine light
  5. Decreased fuel efficiency

How to Fix P0999

  1. Diagnose the code using a scan tool to verify the issue and pinpoint the exact cause of the high voltage condition.
  2. Inspect the wiring harness and connectors for any signs of damage, corrosion, or loose connections. Repair or replace as necessary.
  3. Test the Shift Solenoid 'F' for proper operation and replace if found to be faulty.
  4. Check and top off transmission fluid levels if low.
  5. Clear the code and perform a test drive to ensure the issue has been resolved.

Cost to Fix P0999

The cost of repairing a Shift Solenoid 'F' Control Circuit High issue can vary depending on the root cause of the problem and the vehicle's make and model. On average, the parts for a shift solenoid replacement can range from $50 to $300, while the labor costs can range from $100 to $300. Overall, the total repair cost for this issue could be anywhere from $150 to $600. It is recommended to consult with a professional mechanic to get an accurate estimate based on the specific circumstances of the vehicle.

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Code P0999 Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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