What P0842 means
Circuito del sensor/interruptor A de presión del fluido de la transmisión bajo
How to diagnose
- Read freeze frame data. When P0842 set, your ECU snapshotted every sensor at that moment. This tells you what the car was doing when the fault triggered — RPM, load, coolant temp, throttle position, fuel trims. Almost always enough info to figure out the cause without further testing.
- Check for related codes. If you have P0842 plus other codes, fix the earliest one in the chain first — a single root cause often triggers multiple codes.
- Cheap fixes first. For most codes, the order is: inspect connectors + wiring (free), check for vacuum leaks (cheap), replace sensor (moderate), replace mechanical part (expensive). Follow that ladder before dropping money on parts.
Manufacturer-specific descriptions
Different manufacturers use P0842 for slightly different failure modes:
| AUDI | Transmission Control Module (TCM) failure, Transmission fluid level is low, Transmission fluid pressure sensor failure, Wiring issue |
| BMW | Transmission Fluid Pressure Sensor/Switch "A" Circuit Low |
| HONDA | Short in 2nd Clutch Transmission Fluid Pressure Switch Clutch, or 2nd Clutch Transmission Fluid Pressure Switch (Clutch) Stuck ON |
| MITSUBISHI | Transmission Fluid Pressure Sensor/Switch A Circuit Low |
| NISSAN | Transmission Fluid Pressure Sensor/Switch A Circuit Low |
Read P0842 on your own car
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