Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
Your car's computer is saying that the part that helps change gears is getting too much power.
The P0999 code indicates that the powertrain control module (PCM) has detected a high voltage condition in the shift solenoid F control circuit.
Shift solenoids are used in automatic transmissions to control the flow of transmission fluid and thus the shifting of gears. The 'F' solenoid is one of several in the transmission, and a 'high' circuit condition means the voltage is higher than expected. This could be due to a short circuit or a problem with the solenoid itself.
• Transmission not shifting properly
• Check Engine Light is on
• Poor fuel economy
• Faulty shift solenoid F
• Wiring issues such as a short to power
• Faulty PCM or TCM
PCM: Powertrain Control Module
TCM: Transmission Control Module
Solenoid: An electromechanical device used to control fluid flow in the transmission
• Use a scan tool to check for stored codes and freeze frame data.
• Inspect the wiring and connectors to the shift solenoid F for damage or shorts.
• Test the shift solenoid F for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the shift solenoid F if it is faulty.
• Reprogram or replace the PCM/TCM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $500
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regular transmission fluid changes
• Inspect wiring regularly for wear
• Avoid harsh driving conditions
Transmission Control Issue
• Avoid driving the vehicle until repaired to prevent further damage.
• Consult a professional mechanic for diagnosis and repair.
Check with the vehicle manufacturer for warranty coverage on transmission components.
This code has been associated with wiring issues and solenoid failures in older models.
High – Driving with this code can cause further transmission damage.
Ignoring this code can lead to transmission failure, which may result in unsafe driving conditions.
• Vehicle must be in a safe location.
• Transmission fluid should be at operating temperature.
Inside the transmission, part of the valve body assembly.
Q: Can I drive with a P0999 code?
A: It's not recommended as it can lead to further transmission damage.
Q: How do I reset the Check Engine Light after fixing the issue?
A: Use an OBD-II scanner to clear the code after repairs.
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