P0966 Pressure Control Solenoid B Control Circuit Low

P0966 indicates a low pressure control solenoid B control circuit signal. The solenoid control path is lower than expected.

Code details

Generic OBD-II · P0

System: Transmission
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace hydraulic parts before testing the low control-circuit condition for pressure solenoid B.

Symptoms of P0966

Harsh, delayed, or slipping shifts, or being stuck in one gear.
Check-engine light, sometimes with limp-home mode.
Flaring RPM or a shudder under load.

Common causes of P0966

Low or degraded transmission fluid.
A failing speed sensor, shift solenoid, or pressure-control circuit.
Wiring, connector, or internal hydraulic/mechanical faults.

Useful checks before replacing parts

Check for short-to-ground, low resistance, damaged insulation, connector contamination, and driver-control behavior.
Compare solenoid command with circuit voltage or current and transmission pressure response.
Inspect shared power feeds and grounds if other solenoid control-circuit low codes are present.

Related OBD-II codes

These nearby transmission entries can help compare wording and pin down the fault area.