Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
Your car has a part that helps it change gears, and it's not getting enough power to work properly.
The transmission control module has detected a low voltage or open circuit in the shift solenoid G control circuit.
The P099B code indicates that the transmission control module (TCM) has detected an electrical problem in the circuit that controls the shift solenoid labeled 'G'. This solenoid is responsible for controlling hydraulic pressure to change gears in the automatic transmission. A 'low' circuit condition means the TCM is receiving a voltage signal lower than the expected range.
• Check Engine Light is on
• Transmission may not shift properly
• Reduced fuel efficiency
• Faulty shift solenoid G
• Wiring issues such as open or short circuits
• Faulty transmission control module
Shift Solenoid: An electromechanical device that controls fluid flow in the transmission.
Transmission Control Module (TCM): A computer that controls the operation of the transmission.
• Check for stored codes and freeze frame data using an OBD-II scanner.
• Inspect the wiring and connectors for damage or corrosion.
• Test the shift solenoid G for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the faulty shift solenoid G.
• Replace or reprogram the transmission control module if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regular transmission fluid changes
• Routine inspection of transmission wiring
• Avoiding harsh driving conditions
Transmission Control Circuit Issue
• Avoid driving at high speeds until the issue is resolved.
• Consult a professional mechanic for accurate diagnosis.
Check your vehicle's warranty coverage as transmission components may be covered under powertrain warranty.
This code has been associated with transmission issues in various models, often due to wiring problems or solenoid failures.
Moderate – It is advisable to address this issue soon to prevent further transmission damage.
Driving with transmission issues can lead to unsafe driving conditions. It is recommended to have the vehicle inspected and repaired promptly.
• Vehicle in park or neutral
• Engine at operating temperature
The shift solenoid G is located inside the transmission, usually attached to the valve body.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to further transmission damage and potential safety risks while driving.
Q: Can I drive my car with this code?
A: It's possible to drive short distances, but it's not recommended due to potential shifting issues.
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