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 something is wrong with the part of the car that helps it change gears. It's like when a toy robot can't move its arm because the wire inside is broken or not connected properly.
The P1802 code indicates that the transmission control module (TCM) has detected a low voltage or open circuit condition in the shift solenoid 'B' circuit.
Shift solenoids are used in automatic transmissions to control the flow of hydraulic fluid, which in turn controls gear shifts. The 'B' solenoid is one of several solenoids responsible for these operations. A 'circuit low' condition suggests that the electrical circuit for this solenoid is not receiving the correct voltage, possibly due to an open circuit, short to ground, or a failed solenoid.
• Transmission may not shift properly
• Check Engine Light illuminated
• Harsh or delayed gear shifts
• Transmission stuck in one gear
• Faulty shift solenoid 'B'
• Open or shorted wiring in the shift solenoid circuit
• Poor electrical connection at the transmission control module
• Faulty transmission control module
Shift Solenoid: An electromechanical valve used to control the flow of transmission fluid.
Transmission Control Module (TCM): An electronic device that manages the operation of a vehicle's transmission.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage or corrosion.
• Test the shift solenoid 'B' for proper operation.
• Check the transmission control module for faults.
• Repair or replace damaged wiring or connectors.
• Replace the shift solenoid 'B' if faulty.
• Repair or replace the transmission control module if necessary.
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $400
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regular transmission fluid changes
• Inspect wiring and connectors periodically
• Avoid harsh driving conditions
Transmission Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if you experience shifting problems.
Check with your vehicle manufacturer for specific warranty coverage on transmission components.
This code has historically been associated with common transmission issues in older vehicles, especially those with high mileage.
Moderate – Addressing this issue promptly can prevent further transmission damage.
Driving with a malfunctioning transmission can be dangerous. Always ensure your vehicle is in proper working condition.
• Vehicle at operating temperature
• Transmission in drive
The shift solenoid 'B' is located inside the transmission, usually accessible by removing the transmission pan.
Q: Can I drive with a P1802 code?
A: It's not recommended to drive for extended periods with this code, as it may lead to further transmission damage.
Q: How can I reset the Check Engine Light?
A: You can reset the light using an OBD-II scanner, but it's important to fix the underlying issue first.
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.