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 the car's computer is having trouble getting a steady reading from a sensor that checks the pressure of the fluid in the transmission. It's like trying to listen to a radio station that keeps going in and out.
The P0849 code indicates an intermittent issue with the transmission fluid pressure sensor/switch B circuit, which affects how the transmission operates.
The transmission fluid pressure sensor/switch B is part of the system that monitors the pressure of the transmission fluid. This sensor sends signals to the engine control module (ECM) to ensure the transmission is working correctly. An intermittent signal means the sensor is not consistently sending the correct information, which can lead to improper transmission operation.
• Check Engine Light is on
• Transmission shifting problems
• Erratic transmission behavior
• Faulty transmission fluid pressure sensor/switch
• Wiring issues or poor connections in the sensor circuit
• ECM issues
ECM: Engine Control Module
OBD-II: On-Board Diagnostics, Second Generation
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage or corrosion.
• Test the transmission fluid pressure sensor/switch for proper operation.
• Replace the faulty transmission fluid pressure sensor/switch.
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Honda Accord
• Toyota Camry
• Ford F-150
• Regular transmission fluid checks
• Routine vehicle maintenance
• Inspect wiring and connectors periodically
Sensor Issue
• Have the vehicle inspected by a professional if the Check Engine Light is on.
• Avoid driving the vehicle hard until the issue is resolved.
Check with your vehicle's manufacturer for warranty coverage on transmission components.
This code has been reported in vehicles with high mileage or those that have not had regular transmission maintenance.
Moderate – It is advisable to address this issue soon to avoid potential transmission damage.
Driving with a malfunctioning transmission can be dangerous. Ensure repairs are done promptly to maintain vehicle safety.
• Vehicle at operating temperature
• Transmission in gear
The transmission fluid pressure sensor/switch is typically located on the transmission housing.
Q: Can I drive with a P0849 code?
A: It's possible, but not recommended. Driving with this code can lead to further transmission damage.
Q: How often should transmission fluid be checked?
A: Transmission fluid should be checked at least once a year or as recommended by your vehicle's manufacturer.
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.