Powertrain
generic / SAE
P0840
Transmission Fluid Pressure Sensor/Switch A Circuit Range/Performance
The transmission fluid pressure sensor A reading is implausible compared to commanded line pressure. The TCM detects sensor drift or hydraulic leakage.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number8 / 40
Possible causes
- Pressure sensor drift high
- Internal hydraulic leak medium
- Sensor element aged beyond calibration window low
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 400–2500 €
- Estimated time: 2–8 h
- Component: transmission fluid pressure sensor
- Component: valve body
- Component: transmission pump
- MIL / check engine light
Sources
References
sae:J2012