When a vehicle has a P0966 DTC, it means that the ECU has detected a low voltage signal coming from the pressure control solenoid B circuit. This means that the vehicle computer may not be in full control of the transmission fluid pressure, which can result in serious drivability issues.
What Transmission Do I Have?
How Serious is the Code?
The severity of a P0966 diagnostic trouble code may not be too bad at first. But the transmission problems associated with this OBD2 code will eventually cause your vehicle to become almost undrivable.
Symptoms
Symptoms of a P0966 include:
- Transmission slips between gears
- Unusually harsh shifts
- Overheated transmission
- Engine stalling
- Engine misfire-like symptoms
- Limp mode
Causes
- Dirty transmission fluid
- Clogged transmission filter
- Damage to the wiring and/or connectors
- Pressure control solenoid malfunction
- Transmission pump malfunction
- Valve body failure
- TCM/ECU problems
How to Diagnose the Code?
Diagnosing a P0966 OBDII trouble code should start with a check of the transmission fluid. If it’s clean and topped off, then the wiring and connectors along the transmission wiring harness will need to be inspected. If no damaged wires or broken connectors are found, then further mechanical troubleshooting will need to be done for the pressure control solenoid(s), valve body, transmission pump and possibly the TCM or ECU.
What Transmission Do I Have?
What Repairs Will Fix P0966?
- Change the transmission fluid and filter
- Repair or replace damaged wiring and connectors
- Install new pressure control solenoid(s)
- Repair or replace transmission pump
- Repair or replace the valve body
- Reprogram or replace the ECU or TCM
Related Codes
- P0964 – Pressure Control Solenoid “B” Control Circuit/Open
- P0965 – Pressure Control Solenoid “B” Control Circuit Range/Performance
- P0967 – Pressure Control Solenoid “B” Control Circuit High
