What Does P0847 Mean?
The TCM has detected that the voltage from the transmission fluid pressure sensor/switch "B" circuit is below the minimum allowable threshold. This low voltage indicates a potential short to ground in the wiring, an internally shorted sensor, or a connector fault. The TCM will use a default pressure value for the B circuit.
Common Causes
35%
Internally shorted transmission fluid pressure sensor B
30%
Short to ground in sensor B signal wiring
20%
Corroded or contaminated connector creating a ground path
10%
Transmission fluid contamination affecting sensor
5%
TCM reference circuit fault
Diagnostic Steps
1
Verify the pressure sensor B PID reads near-zero voltage, confirming the low circuit condition.
2
Disconnect the sensor B connector and check if the signal voltage at the TCM rises to reference voltage; if so, the sensor is shorted.
3
Measure the sensor resistance — abnormally low resistance confirms internal failure.
4
With the sensor disconnected, check the signal wire for continuity to chassis ground (there should be none).
5
Inspect the internal transmission harness connector for fluid contamination, corrosion, or damaged insulation.
Estimated Repair Cost
$200 - $800
Parts + labor, varies by vehicle and location
The TCM has detected that the voltage from the transmission fluid pressure sensor/switch "B" circuit is below the minimum allowable threshold. This low voltage indicates a potential short to ground in the wiring, an internally shorted sensor, or a connector fault. The TCM will use a default pressure...
The most common cause of P0847 (Transmission Fluid Pressure Sensor/Switch "B" Circuit Low) is: Internally shorted transmission fluid pressure sensor B
Typical repair costs for P0847 range from $200 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The transmission will use default pressure values for the B circuit, resulting in potentially harsh or inconsistent shifts. Drivable for short distances; repair soon to prevent further transmission wear.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0847 to identify the root cause.
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Quick Info
Category
Powertrain
System
Automatic Transmission
Difficulty
Type
Generic (SAE)
Recommended Tools
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