P0846 code meaning
Transmission Fluid Pressure Sensor/Switch B Circuit Range/Performance
Powertrain system Generic code P08xx codes Check engine light
What P0846 means
Transmission fluid pressure sensor/switch A and B are inputs inside the automatic gearbox. A switch only reports pressure present or absent, a sensor reports a value. The letter is the maker's choice: Allison 1000 uses A and B for the switches on shift valves S1 and S2, GM's CVT for the primary and secondary pulley sensors, GM's 2025 8-speed A for the lube pressure sensor; Ford reports pressure faults under its solenoid codes instead. P0846 is the plausibility fault of B. GM's CVT uses the same test as for A on its second pulley: pressure off target by 500 or 1500 kPa plus a ratio error above 0.2 for about 6 s, line pressure above 600 kPa, over 35 km/h, type A. Allison sets it when switch 2 stays without pressure 5 s after valve S2 is applied. On the Corvette dual clutch a sticking valve is the usual cause.
P0846 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 8 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0846
- Check engine or transmission warning lamp on
- Slipping or shift shock
- CVT: ratio and power limited
Common causes of P0846
- Most likelyDirty or sticking valve, worn valve body
- Most likelyPressure sensor or switch drifting or sticking
- PossibleFluid level low, fluid aged or filter clogged
- PossibleMechanical damage: thrust washer, CVT belt or pulley, pump
- Less likelyControl module software
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Transmission fluid pressure sensorTransmission valve bodyTransmission wiringTransmission control module
What each part of P0846 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 8 | Area: transmission. |
| 46 | The exact fault in that area. |
What to do next
- Note P0846 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 P0846
What does P0846 mean?
P0846 means "Transmission Fluid Pressure Sensor/Switch B Circuit Range/Performance". Transmission fluid pressure sensor/switch A and B are inputs inside the automatic gearbox. It is a generic code, so it means the same on every make.
Is it safe to drive with P0846?
Drive gently and only to a workshop. With P0846 the car can go into limp mode (reduced power) to protect itself.
Will P0846 fail an emissions test?
Yes, it can. P0846 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 P0846 to fix?
Difficulty: hard. A typical repair takes 1 to 8 hours of work. This is a job for a workshop.
Will P0846 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.