P07BD: Transmission Park Position Sensor/Switch B Circuit Intermittent/Erratic

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. P07BD means sensor B's signal jumps or drops out intermittently. No manufacturer document available to us uses this code; GM covers intermittent P button problems as zone or correlation faults (P07BB, P07BE). A loose contact in the selector connector is the likely cause.

Symptoms

• 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

Most likely causes

• Loose contact in the selector connector or harness
• Sensor with intermittent fault
• Off-centre pressing or a hand resting on the button

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the fluid level and condition
2. Gently move the wiring with the engine running and watch whether the reading changes.
3. Read the input and output speed in live data
4. Check the connector and wiring
5. Check for other related engine codes
6. Consult the manufacturer's procedure for the transmission

Good to know

• Repair difficulty: medium
• It can trigger limp mode.

What each character of P07BD means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 7: Transmission
• BD: Specific fault in that system

Frequently asked questions

Can I keep driving with code P07BD?

Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.

What causes code P07BD?

The most common causes are: loose contact in the selector connector or harness; sensor with intermittent fault; off-centre pressing or a hand resting on the button.

Related codes

• P07B9Transmission Park Position Sensor/Switch B Circuit Low
• P07BATransmission Park Position Sensor/Switch B Circuit High
• P07BBTransmission Park Position Sensor/Switch B Circuit Performance/Low
• P07B7Transmission Park Position Sensor/Switch A Circuit Intermittent/Erratic
• P07BETransmission Park Position Sensor/Switch A/B Correlation

Sources

• law.cornell.edu: 13 CCR 1968.2
• static.nhtsa.gov: MC 10165888 9999

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.