What it means
The signal in park position sensor or switch A circuit is below the expected range.
At a glance
- Usually lights the check-engine light
How it works
Park position sensor or switch A sends a signal to the transmission control module on circuit A. P07B3 sets when that signal falls below the expected range, which can happen if the wire is grounded or the connection is degraded; it identifies a low signal, not a high one.
Common causes
Most likely first.
- Wire shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Capture freeze-frame data and inspect live data for the park sensor or switch A reading and when it drops low.
- Inspect circuit A from sensor A to the module for chafing, crushed insulation, corrosion, or a pin contacting ground.
- Check connector terminals for corrosion or weak contact, since resistance at a connection can pull the signal below its expected range.
- Use the wiring diagram and manufacturer's test procedure to measure circuit A and check for an unintended short to ground.
- If the wiring and connectors pass, test sensor or switch A and the module input against the manufacturer's specification.
Common fixes
- Clean and secure corroded or loose circuit A connector terminals.
- Repair chafed or crushed wiring that is shorting circuit A to ground.
- Replace sensor or switch A if its output remains low during the specified test.
- Repair the module input only after circuit and sensor tests isolate the fault there.
Can I keep driving?
Use the parking brake and confirm the vehicle is secure when parked, because an incorrect park signal can affect transmission control. Avoid driving if the gear display or shifting becomes unreliable, or if the transmission slips or enters limp mode.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.