P07B9
Transmission Park Position Sensor/Switch B Circuit Low
Transmission (park/neutral position switch)
Generic OBD-II
Medium
What it means
P07B9 means the signal from transmission park-position sensor/switch B is reading too low — a short to ground or an open. This switch tells the vehicle when the selector is in Park, which many cars use to allow the engine to crank, so a fault can cause no-crank conditions or an incorrect gear-position reading. It usually points to the switch itself or its wiring.
Medium
Can I keep driving? The engine may refuse to crank unless it's in Park or Neutral and the gear indicator can read wrong; usually still drivable once started, but fix it soon.
Common symptoms
What you'll notice
- Engine may not crank unless the shifter is moved (Park/Neutral not confirmed)
- Wrong or missing gear-position (PRNDL) indicator
- Rough or unexpected shifting
- Check-engine light on
Common causes
Most likely first
- Faulty or misadjusted transmission park-position switch/sensorLikely
- Short to ground or open in the switch wiring (circuit reads low)Common
- Corroded or damaged connector at the switchCommon
- Wiring harness damage near the transmissionLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame and inspect the park-position switch connector and wiring for shorts, corrosion, or damage.
- Verify the switch is correctly adjusted and aligned to the selector.
- Measure the switch signal across gear positions and compare to spec.
- Replace the park-position switch/sensor if it reads out of range.
- Repair any harness short-to-ground found in the circuit.
FAQ
Quick answers
Is it safe to drive with P07B9?+
Once the engine starts it's usually driveable, but the fault can cause intermittent no-crank and a wrong gear display, so have it repaired soon.
Can I just clear P07B9?+
It will set again while the circuit reads low; the switch or its wiring short needs to be found and fixed first.
Related codes
Often seen with P07B9
Read & clear P07B9 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX