P0966 code meaning
Pressure Control Solenoid B Control Circuit Low
Powertrain system Generic code P09xx codes Check engine light
What P0966 means
Pressure control solenoid B circuit low, meaning a short to ground in the driver circuit. On GM's six-speeds and the Saab 9-4X 6T70, B is clutch pressure solenoid 2 for the 3-5-reverse clutch; a short lasting 0.3 s (GM 2018 table) or 1 s (Saab) sets a Type A code with a fixed limp mode: reverse and 5th gear, maximum line pressure, converter clutch off. GM's 8-, 9- and 10-speeds use B for a clutch solenoid and treat less than 0.5 ohm as a short; Allison 1000 uses it for pressure control solenoid 2 with ground-short detection in 125 ms. Ford does not use the B codes. Siblings are P0964 open, P0967 high and P0965 performance; solenoids A and C follow the same scheme.
P0966 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0966
- MIL on immediately
- Limp mode with reverse and one forward gear
- No torque converter lock-up, higher fuel consumption
Common causes of P0966
- Most likelyChafed control wire touching ground
- PossibleInternally shorted solenoid in the valve body assembly
- PossibleFluid or moisture in the connector
- Less likelyFaulty output stage in the control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Pressure control solenoid bWiring harnessTCM
What each part of P0966 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 9 | Area: transmission. |
| 66 | The exact fault in that area. |
What to do next
- Note P0966 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0966
What does P0966 mean?
P0966 means "Pressure Control Solenoid B Control Circuit Low". Pressure control solenoid B circuit low, meaning a short to ground in the driver circuit. It is a generic code, so it means the same on every make.
Is it safe to drive with P0966?
Drive gently and only to a workshop. With P0966 the car can go into limp mode (reduced power) to protect itself.
Will P0966 fail an emissions test?
Yes, it can. P0966 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0966 to fix?
Difficulty: hard. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will P0966 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.