Pressure Control Solenoid "B" Control Circuit/Open
The P0964 code indicates that the Powertrain Control Module (PCM) or Transmission Control Module (TCM) has detected an open circuit or lack of continuity in the control circuit for transmission pressure control solenoid 'B'. The computer sets this code when the electrical feedback from the solenoid circuit does not match the expected voltage or resistance parameters, preventing proper hydraulic pressure regulation.
This code is considered high severity because improper hydraulic line pressure can cause severe internal transmission damage due to slipping clutches. The vehicle may also enter a protective 'limp mode,' significantly limiting speed and drivability.
Common symptoms
- Illuminated Check Engine Light
- Harsh, delayed, or erratic transmission shifting
- Transmission slipping between gears
- Vehicle stuck in 'limp mode' (restricted to a single gear)
- Decreased fuel economy and poor acceleration
Likely causes
- Faulty transmission pressure control solenoid 'B'
- Damaged, corroded, or disconnected wiring in the solenoid 'B' circuit
- Dirty or contaminated transmission fluid restricting solenoid operation
- Low transmission fluid level
- Internal transmission mechanical or valve body failure
- Faulty Transmission Control Module (TCM) or PCM (rare)
What to check before replacing parts
Check the transmission fluid level and condition.
Look for: Fluid that is low, burnt, or heavily contaminated with debris, which indicates fluid starvation or internal transmission wear.
Inspect the wiring harness and connectors associated with pressure control solenoid 'B'.
Look for: Loose connections, broken wires, pushed-out pins, or corrosion that would cause an open circuit.
Measure the internal resistance of pressure control solenoid 'B' using a digital multimeter.
Look for: Resistance readings outside the manufacturer's specified range, or an 'OL' (open loop) reading indicating an internal break in the solenoid coil.
Test the circuit continuity between the TCM/PCM and the transmission solenoid connector.
Look for: High resistance or an open circuit in the wiring harness between the control module and the transmission.
Command solenoid 'B' on and off using a bidirectional scan tool.
Look for: Lack of an audible click from the solenoid or no change in transmission line pressure on the scanner data, confirming the solenoid or circuit is inactive.
This page explains the generic P0964 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
Gear guide: Best OBD2 ScannersRead this code yourself next time — from $20 Bluetooth dongles to bidirectional scan tools.Rather have a pro handle it? Find a vetted local mechanic.