Transmission Park Position Sensor/Switch Circuit Low
The P07B9 code indicates that the transmission control module (TCM) has detected a low voltage or resistance in the park position sensor/switch circuit. This sensor tells the TCM when the transmission is in Park, which is critical for starting the engine and engaging the parking pawl. A low circuit condition can be caused by a faulty sensor, damaged wiring, or a poor electrical connection. This issue may prevent the engine from starting or cause the transmission to behave unexpectedly.
01. Most Common Causes
- Faulty park/neutral position switch
- Damaged or corroded wiring/connectors
- Low battery voltage or charging system issue
- TCM software or hardware failure
02. Symptoms You Will Notice
- Engine may not start in Park or Neutral
- Check Engine Light illuminated
- Transmission stuck in Park or fails to shift
- Intermittent starting issues
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Inspect the park/neutral position switch and its wiring for damage or corrosion.
Step 3: Test the switch resistance and voltage with a multimeter; compare to manufacturer specs.
Step 4: Check battery voltage and charging system; repair if low.
Step 5: If all else passes, update TCM software or replace TCM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The vehicle may not start or could unexpectedly shift out of Park, posing a safety risk. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
Typically $50-$150 for a switch replacement, but costs can vary if wiring repairs or TCM replacement are needed.