What Does P0873 Mean?
The TCM has detected that the signal voltage from transmission fluid pressure sensor/switch 'C' is above the maximum expected threshold. A high circuit reading typically indicates a short to battery voltage, an open ground wire, or a sensor that has failed in a way that produces excessive output voltage. The TCM cannot accurately determine hydraulic pressure in this circuit.
Common Causes
30%
Open ground wire in sensor 'C' circuit
28%
Failed transmission fluid pressure sensor 'C' (open internally)
22%
Signal wire shorted to voltage source
12%
Corroded or disconnected sensor connector
8%
TCM internal pull-up circuit malfunction
Diagnostic Steps
1
Measure the voltage at the pressure sensor 'C' signal wire — if it reads near 5V or battery voltage, the signal is being pulled high.
2
Verify the sensor ground wire has good continuity to the TCM ground and to chassis ground (less than 0.5 ohms).
3
Disconnect the sensor and check if the signal drops — if it stays high, the issue is in the wiring; if it drops, the sensor is faulty.
4
Inspect the wiring for chafing against transmission housing or other components that could cause a short to voltage.
5
If wiring is intact and sensor is suspect, replace pressure sensor 'C' and verify proper signal range.
Estimated Repair Cost
$100 - $500
Parts + labor, varies by vehicle and location
The TCM has detected that the signal voltage from transmission fluid pressure sensor/switch 'C' is above the maximum expected threshold. A high circuit reading typically indicates a short to battery voltage, an open ground wire, or a sensor that has failed in a way that produces excessive output vol...
The most common cause of P0873 (Transmission Fluid Pressure Sensor/Switch "C" Circuit High) is: Open ground wire in sensor 'C' circuit
Typical repair costs for P0873 range from $100 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The transmission may enter limp mode or exhibit harsh shifting due to incorrect pressure data. Limit driving to essential trips and avoid towing until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0873 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission Hydraulic Pressure Monitoring
Difficulty
Type
Generic (SAE)
Recommended Tools
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