What Does P07B8 Mean?
The transmission park position sensor/switch "B" circuit has an open condition. This is the secondary or redundant park position sensor, and the TCM has detected a complete loss of signal from it. An open circuit means the signal wire is broken, disconnected, or the sensor has an internal open failure. Many modern transmissions use dual park sensors (A and B) for validation, and losing sensor B means the TCM cannot cross-reference Park position detection.
Common Causes
35%
Damaged or disconnected wiring harness between park position sensor B and TCM
30%
Failed park position sensor/switch B with internal open circuit
20%
Corroded or backed-out connector pins at sensor B or TCM connector
10%
TCM internal failure on the sensor B input circuit
5%
Broken wire from transmission vibration or routing interference
Diagnostic Steps
1
Inspect the park position sensor B connector at the transmission for physical damage, disconnection, corrosion, or backed-out pins.
2
Measure continuity of the sensor B signal circuit from the sensor connector back to the TCM connector using a multimeter.
3
Verify supply voltage and ground are present at the sensor B connector with the ignition on.
4
Test sensor B by measuring resistance or voltage output while cycling through all gear positions — compare to specifications.
5
If wiring and sensor test correctly, inspect the TCM connector for damage and consider TCM failure on the sensor B input.
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
The transmission park position sensor/switch "B" circuit has an open condition. This is the secondary or redundant park position sensor, and the TCM has detected a complete loss of signal from it. An open circuit means the signal wire is broken, disconnected, or the sensor has an internal open failu...
The most common cause of P07B8 (Transmission Park Position Sensor/Switch "B" Circuit Open) is: Damaged or disconnected wiring harness between park position sensor B and TCM
Typical repair costs for P07B8 range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
With sensor B failed, the TCM relies solely on sensor A for Park detection, reducing the redundancy built into the system. The vehicle may still operate but with reduced safety margin for Park verification. No-start conditions are possible if the TCM requires both sensors. Repair promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P07B8 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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