P0847: Transmission Fluid Pressure Sensor/Switch B Circuit Low
What to do
Ask for a mechanical gauge reading rather than relying on the scan tool, which reads the suspect sensor. If the transmission is slipping as well, treat lost pressure as the working assumption until the gauge says otherwise.
What this code means
The second pressure sensor circuit reads below its valid electrical range, typically a short to ground. The same distinction that governs P0842 applies here: a circuit reading low and a genuine loss of pressure are indistinguishable to the module, and a mechanical gauge on the test port is what separates them.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Faulty transmission fluid pressure sensor · moderate
- Low or degraded transmission fluid · easy
Less common
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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