P0841Transmission Fluid Pressure Sensor/Switch A Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- Check engine or transmission warning lamp on
- Shift shock, slipping or delayed engagement
- CVT: ratio and power limited
- Likely causes
- LikelyDirty or sticking valve, worn valve body
- LikelyPressure sensor or switch drifting or sticking
- PossibleFluid level low, fluid aged or filter clogged
- PossibleMechanical damage: thrust washer, CVT belt or pulley, pump
- RareControl module software
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.