Powertrain, generic · Transmission

P07B4 Transmission Park Position Sensor/Switch A Circuit High

Check engine lightOn
EmissionsNot relevant
Drive cycleRequired
Limp modePossible

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. P07B4 means sensor A reads above its valid zones: GM flags above 853 counts (83.3 % of 5 V), the ICCM above 70 %, after two trips. A short to positive or an open ground is typical. A GM bulletin for the 2017 LaCrosse, XT5 and Bolt EV lists P07B4 when the selector knob is not fully seated or the connector at the shifter is not latched – check that first.

Likely causes

Signal shorted to positive or ground open
Selector knob not fully seated or connector not latched
Sensor in the P button faulty
Selector or control module

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

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–600
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

park position sensorelectronic range selectorsensor wiringtransmission control module

Related codes

P07B3P07B5P07B6P07BAP07BE

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.