P07B8 code meaning
Transmission Park Position Sensor/Switch B Circuit/Open
Powertrain system Generic code P07xx codes Check engine light
What P07B8 means
With electronic gear selection the park position sensor/switch reports the park request or position. On GM's shift-by-wire selectors (2017 LaCrosse, XT4/XT5, Bolt EV, later SUVs and pickups) it is the P button, read by two redundant analog sensors A and B with separate 'released' and 'pressed' voltage zones. P07B8 means the circuit of the redundant sensor B is open. No manufacturer document available to us uses this code; GM covers an open analog circuit under its low and high codes (P07B9/P07BA). With one channel missing, the module can no longer cross-check the park request.
P07B8 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P07B8
- Check engine light, 'service transmission' or 'unable to shift' message
- Park cannot be selected by button, or the car will not shift out of P
- P button illumination off
Common causes of P07B8
- Most likelyWire or connector to the selector open
- PossibleConnector not latched
- PossibleSensor faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Park position sensorElectronic range selectorSensor wiringTransmission control module
What each part of P07B8 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7 | Area: transmission. |
| B8 | The exact fault in that area. |
What to do next
- Note P07B8 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P07B8
What does P07B8 mean?
P07B8 means "Transmission Park Position Sensor/Switch B Circuit/Open". With electronic gear selection the park position sensor/switch reports the park request or position. It is a generic code, so it means the same on every make.
Is it safe to drive with P07B8?
Drive gently and only to a workshop. With P07B8 the car can go into limp mode (reduced power) to protect itself.
Will P07B8 fail an emissions test?
P07B8 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P07B8 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P07B8 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.