Powertrain, generic · Transmission

P09A5 Gate Select Position Circuit B High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Indicates that the gate select signal on circuit B has stayed above its highest valid value for longer than allowed. Typical reasons are a short of the signal wire to the sensor supply or battery voltage, an open sensor ground, or a defective sensor. No manufacturer publishes how it uses this code or what circuit B physically is. An Aisin AI patent shows the consequence of losing select feedback: warning, request to stop, then a limp-home in first gear. CARB requires out-of-range checks on such inputs. P09A4 is the low counterpart, P09A2 the general fault, P0907 and P09A9 the high faults of circuits A and C. A gearbox that can no longer confirm its gate restricts shifting.

Likely causes

Signal wire of circuit B shorted to sensor supply or battery voltage
Open sensor ground or corroded ground pin
Internal fault of the select sensor
Faulty input stage in the transmission control module

Symptoms

  • Check engine or transmission warning light on
  • Gearbox stays in one gear or in neutral
  • Limp-home mode with very limited gear choice

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–1,500
Time0.5–4 h

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

Parts involved

gate select position sensor bwiring harnesstcm

Related codes

P09A2P09A3P09A4P0907P09A9

References: law.cornell.edu, patents.google.com, patents.google.com.