What it means
The transmission control module detected an open circuit in park position sensor or switch B.
At a glance
- Usually lights the check-engine light
How it works
Park position sensor or switch B provides park-related information to the transmission control module through circuit B. P07B8 sets when the module detects an open circuit in that B path, so it loses electrical continuity from sensor or switch B.
Common causes
Most likely first.
- Open wire or unplugged sensor
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
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
- Record freeze-frame data and scan transmission live data for the reported state of park sensor or switch B and any related codes.
- With the vehicle secured, inspect sensor B's connector and wiring for a disconnected plug, damaged insulation, or a terminal pushed back into the connector.
- Trace circuit B between sensor or switch B and the module using the vehicle wiring diagram, looking for a break or poor connection.
- With power isolated as specified by the manufacturer, test circuit B for continuity and check that its terminals make secure contact.
- If circuit B passes, test sensor or switch B and the module input according to the manufacturer's procedure before replacing parts.
Common fixes
- Reconnect a loose sensor B plug and secure its harness.
- Repair a broken wire or backed-out terminal in circuit B.
- Repair or replace a damaged connector or sensor B with a verified open circuit.
- Repair an internal sensor or module solder joint only if testing confirms the open is there.
Can I keep driving?
The code does not establish park interlock or starting behavior, so confirm the vehicle is securely in Park and use the parking brake whenever parked. If gear indication, starting, or shifting is abnormal, avoid driving until checked.
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.