Powertrain, generic · Transmission

P09A2 Gate Select Position Circuit B

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

General electrical fault on the second gate select position signal (circuit B) of an automated manual gearbox. The published designs from Isuzu (one select potentiometer) and Aisin AI (one select stroke sensor) show only a single sensor, so it is not documented whether B is a redundant second track of that sensor or a separate sensor. No manufacturer documents this code publicly. CARB requires circuit checks on such inputs. P09A4 and P09A5 are the more specific low and high faults of circuit B, P09A3 its plausibility fault; unlike circuit A (P0908) there is no intermittent variant. P0904 and P09A6 cover circuits A and C. Expect shifting to be restricted.

Likely causes

Loose, corroded or wet connector at the select sensor or actuator unit
Chafed or broken signal wire of circuit B near the gearbox
Faulty select sensor, often integrated in the shift and select actuator
Faulty input stage for circuit B in the transmission control module

Symptoms

  • Check engine or transmission warning light on
  • Gearbox shifts slowly or locks out certain gears
  • Gearbox stays in one gear or neutral

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
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

P09A3P09A4P09A5P0904P09A6P0909

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