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Code P0966

Symptoms

• Harsh or erratic shifting

• Transmission slipping

• Illuminated check engine light

Common Causes

• Faulty pressure control solenoid B

• Wiring issues such as short or open circuits

• Faulty transmission control module (TCM)

Glossary

Solenoid: An electromechanical device that controls the flow of fluid.

TCM: Transmission Control Module, the computer that controls transmission functions.

Related Codes

• P0965

• P0967

Official description

Pressure Control Solenoid B Control Circuit Low

Laymans terms

This code means that the car's computer has detected a problem with the electrical circuit that controls one of the pressure control parts in the transmission. It's like when a light switch doesn't work because the wires are loose.

Explanation

The code P0966 indicates that the transmission control module (TCM) has detected a low voltage or open circuit condition in the pressure control solenoid B control circuit.

Technical description

Pressure control solenoids are used in automatic transmissions to regulate hydraulic pressure. The solenoid B is responsible for controlling the pressure applied to specific transmission components. A low circuit condition suggests a problem with the electrical signal reaching the solenoid, which can affect transmission performance.

Diagnosis steps

• Use an OBD-II scanner to confirm the code.

• Inspect the wiring and connectors for damage or corrosion.

• Test the pressure control solenoid B for proper operation.

Repair procedures

• Repair or replace damaged wiring or connectors.

• Replace the faulty pressure control solenoid B.

• Reprogram or replace the transmission control module if necessary.

Tools required

• OBD-II scanner

• Multimeter

• Basic hand tools

Estimated repair cost

$150 - $500

Difficulty level

Moderate

Commonly affected vehicles

• Honda Accord

• Toyota Camry

• Ford Focus

Preventive measures

• Regularly inspect and maintain transmission fluid levels.

• Ensure wiring and connectors are free from corrosion.

• Perform routine transmission maintenance.

Error code type

Transmission Control Issue

User experience recommendations

• Avoid driving aggressively until the issue is resolved.

• Have the vehicle inspected by a professional mechanic.

• Consider regular transmission service to prevent future issues.

Warranty information

Check with your vehicle manufacturer for specific warranty coverage related to transmission components.

Historical data

This code has been associated with vehicles experiencing transmission performance issues due to electrical problems in the solenoid circuits.

Urgency level

Moderate – It's important to address this issue to prevent potential transmission damage.

Legal and safety notice

Driving with transmission issues can lead to safety hazards. It is advised to address the problem promptly.

Testing conditions

• Vehicle must be at operating temperature.

• Ensure the battery is fully charged.

Component location

The pressure control solenoid B is located inside the transmission, usually accessible by removing the transmission pan.

FAQs

Q: Can I drive with a P0966 code?
A: It's not recommended to drive for extended periods with this code, as it can lead to transmission damage.

Q: How can I prevent this code from appearing again?
A: Regular maintenance and inspection of the transmission system can help prevent this code.

Last updated: Mar 2, 2026 • Source: internal database
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