What P0841 means
Transmission fluid pressure sensor/switch A and B are inputs inside the automatic transmission.
How the engine computer detects it
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 (73 psi) steady or 1500 kPa (218 psi) 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 (5.8 psi) after start-up; Mitsubishi's CVT sets it at 0.675 MPa deviation for 5 s.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine or transmission warning lamp on
- Shift shock, slipping or delayed engagement
- CVT: ratio and power limited
Common causes
- Dirty or sticking valve, worn valve body Most likely
- Pressure sensor or switch drifting or sticking Most likely
- Fluid level low, fluid aged or filter clogged Possible
- Mechanical damage: thrust washer, CVT belt or pulley, pump Possible
- Control module software Less likely
How to diagnose P0841
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: transmission fluid pressure sensor, transmission valve body, transmission wiring, transmission control module.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report P0841 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Nissan Altima | 2013–2017 | 10 | 61k | |
| Volkswagen Jetta | 2013–2015 | 5 | — | |
| Nissan Rogue | 2014–2017 | 4 | — |
Counts of owner complaints to the NHTSA that mention P0841 (32 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 8
- Transmission
- 41
- Specific fault
Questions drivers ask
Can I drive with code P0841?
If the car shifts normally, drive gently to a shop. If it's stuck in one gear, slips, shifts harshly or won't move out of Park, don't drive it: have it towed.
Will my car pass an emissions inspection with P0841?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Often reported together
Codes that owners mention in the same NHTSA complaints as P0841. They can point to a shared cause, so it's worth checking them together.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.