What Does P07B3 Mean?
The transmission park position sensor/switch "A" circuit is reading lower voltage than expected. The TCM monitors the signal voltage from this sensor to determine Park gear engagement status, and the signal is below the normal operating range. This could indicate a short to ground in the circuit, a failed sensor with low resistance, or a ground path issue. The vehicle may have difficulty starting, may not recognize Park position, or may display incorrect gear indicator readings.
Common Causes
35%
Short to ground in the park position sensor A signal wire from chafing or insulation damage
30%
Failed park position sensor A with internal short producing low signal output
20%
Corroded sensor connector allowing moisture intrusion and creating a ground path
10%
Transmission internal wiring harness damage near the sensor creating a short circuit
5%
TCM ground circuit issue affecting sensor A signal reference voltage
Diagnostic Steps
1
Measure the park position sensor A signal voltage at the TCM connector with the transmission in Park — compare to factory specification.
2
Disconnect the sensor and check if the voltage at the TCM rises to reference voltage, confirming a sensor or wire-to-ground short.
3
Inspect the sensor A wiring harness for chafed insulation, pinched wires, or contact with metal surfaces that could cause a ground short.
4
Test the park position sensor A resistance values through all gear positions and compare to manufacturer specifications.
5
Check the sensor connector and TCM connector for moisture intrusion, corrosion, or bent pins that could create a low-resistance path.
Estimated Repair Cost
$120 - $550
Parts + labor, varies by vehicle and location
The transmission park position sensor/switch "A" circuit is reading lower voltage than expected. The TCM monitors the signal voltage from this sensor to determine Park gear engagement status, and the signal is below the normal operating range. This could indicate a short to ground in the circuit, a ...
The most common cause of P07B3 (Transmission Park Position Sensor/Switch "A" Circuit Low) is: Short to ground in the park position sensor A signal wire from chafing or insulation damage
Typical repair costs for P07B3 range from $120 to $550, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle may not start or may not accurately indicate the gear position. The shift interlock system may be compromised. Avoid parking on steep grades until repaired, as the system may not reliably confirm Park engagement. Schedule repair soon.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P07B3 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission Control / Park System
Difficulty
Type
Generic (SAE)
Recommended Tools
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