Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This means that something is wrong with a part in your car that helps it change gears. It's like if a toy robot's arm won't move because the wire controlling it is broken or not getting power.
The code P0979 indicates a problem with the electrical circuit that controls the shift solenoid C in the transmission. The circuit is reading a low voltage, which means the solenoid may not be functioning properly.
P0979 is triggered when the transmission control module (TCM) detects a low voltage condition in the control circuit for shift solenoid C. This solenoid is responsible for controlling the flow of transmission fluid to engage specific gears. A low circuit condition can be caused by wiring issues, a faulty solenoid, or a problem with the TCM itself.
• Transmission slipping or not shifting properly
• Check Engine Light illuminated
• Poor fuel economy
• Faulty shift solenoid C
• Wiring issues such as damaged wires or poor connections
• Faulty transmission control module (TCM)
Shift Solenoid: An electromechanical valve that controls the flow of transmission fluid.
TCM: Transmission Control Module, the computer that controls the transmission.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage or corrosion.
• Test the shift solenoid C for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the shift solenoid C if faulty.
• Replace or reprogram the TCM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Honda Accord
• Toyota Camry
• Ford F-150
• Regular transmission fluid changes
• Routine vehicle maintenance
• Inspect wiring and connectors periodically
Transmission Control Issue
• Avoid driving the vehicle if it's not shifting properly.
• Consult a professional mechanic for a thorough diagnosis.
Check your vehicle's warranty; transmission components may be covered under powertrain warranty.
P0979 has been a common issue in vehicles with electronic transmission control systems, particularly in models from the early 2000s.
Moderate – Address the issue soon to avoid potential transmission damage.
Driving with a malfunctioning transmission can be dangerous. Ensure repairs are conducted by a qualified professional.
• Vehicle at operating temperature
• Transmission in drive mode
Shift solenoid C is typically located inside the transmission, accessible by removing the transmission pan.
Q: Can I drive with a P0979 code?
A: It's not recommended to drive with this code as it can cause further damage to the transmission.
Q: How do I reset the Check Engine Light after repairs?
A: You can reset the light using an OBD-II scanner after fixing the issue.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
View on Amazon
Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.