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. P0841 means the signal is electrically fine but does not match the commanded state. GM's CVT sets it when pulley pressure misses its target by more than 500 kPa steady or 1500 kPa transient while the ratio is off by over 0.2 for about 6 s, type A. GM's 8-speed checks the lube sensor rises above 40 kPa after start-up; Mitsubishi's CVT sets it at 0.675 MPa deviation for 5 s.
Medium severity. Can I keep driving?You can drive gently to a repair shop if the transmission is shifting well, but avoid highways and towing. If it slips, jerks, or goes into limp mode, stop: continuing that way can burn out the internal clutches.
Symptoms
- Check engine or transmission warning lamp on
- Shift shock, slipping or delayed engagement
- CVT: ratio and power limited
Most likely causes
- Dirty or sticking valve, worn valve body
- Pressure sensor or switch drifting or sticking
- Fluid level low, fluid aged or filter clogged
- Mechanical damage: thrust washer, CVT belt or pulley, pump
- Control module software
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It can trigger limp mode.
- It affects emissions.
What each character of P0841 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 8: Transmission
- 41: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0841?
You can drive gently to a repair shop if the transmission is shifting well, but avoid highways and towing. If it slips, jerks, or goes into limp mode, stop: continuing that way can burn out the internal clutches.
What causes code P0841?
The most common causes are: dirty or sticking valve, worn valve body; pressure sensor or switch drifting or sticking; fluid level low, fluid aged or filter clogged.
Related codes
- P0840Transmission Fluid Pressure Sensor/Switch A Circuit
- P0842Transmission Fluid Pressure Sensor/Switch A Circuit Low
- P0843Transmission Fluid Pressure Sensor/Switch A Circuit High
- P0846Transmission Fluid Pressure Sensor/Switch B Circuit Range/Performance
- P0868Transmission Fluid Pressure Low
- P0776Pressure Control Solenoid B Performance/Stuck Off
Sources
- gsi.ext.gm.com: 23OBDG03A Part1
- gsi.ext.gm.com: 25OBDG06A
- static.nhtsa.gov: MC 10211535 0001
- static.nhtsa.gov: SB 10089604 0699
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.