P0843: Transmission fluid pressure sensor/switch A: circuit high
The control unit gets too high a voltage from gearbox fluid pressure sensor A. An open wire, the connector or the sensor is the usual cause.
| Code | P0843 |
|---|---|
| System | Engine and transmission |
| Group | P08xx, Transmission |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P0843 means
The gearbox fluid pressure sensor reports to the control unit through a voltage. Here that voltage is above the possible range, typical of an open circuit or a short to positive rather than genuinely high pressure. What sensor A is is decided by each manufacturer.
Most common causes
- Sensor connector unplugged or with open pins
- Broken sensor earth wire
- Signal wire touching a positive feed
- Faulty pressure sensor or switch itself
- Gearbox control unit fault (rare)
Symptoms
- Engine or gearbox warning light on
- Gearbox in limp mode
- Harsh shifts
Can you drive with P0843?
With care You can drive carefully, but the gearbox may restrict gears. Best to get it to a garage soon.
Open the bonnetthe in-depth explanation
How to check it
Make sure the sensor connector is fully seated with no bent pins. If the live value sits at maximum all the time, an open circuit is almost certain.
How to read and clear P0843 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0843 with its description and whether it’s confirmed, pending or permanent.
This code is usually stored by the gearbox control unit. If the car reports it over standard OBD, you read it for nothing with FREE; to read it straight from the gearbox control unit, with its description and clearing, you need PRO.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P083F Clutch pedal position switches A and B give conflicting signals
- P0840 The gearbox oil pressure sensor A has an electrical fault
- P0841 Transmission fluid pressure sensor/switch A: circuit range or performance
- P0842 Transmission fluid pressure sensor/switch A: circuit low
- P0844 The gearbox oil pressure sensor A fails now and then
- P0845 The gearbox oil pressure sensor B has an electrical fault
- P0846 The gearbox oil pressure sensor B gives readings outside the normal range
- P0847 The gearbox oil pressure sensor B gives a lower signal than normal
- P0868 Transmission fluid pressure low
What does code P0843 mean?
The gearbox fluid pressure sensor reports to the control unit through a voltage. Here that voltage is above the possible range, typical of an open circuit or a short to positive rather than genuinely high pressure. What sensor A is is decided by each manufacturer.
Can you drive with P0843?
You can drive carefully, but the gearbox may restrict gears. Best to get it to a garage soon.
How do you clear P0843?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0843 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
