Powertrain, generic · Transmission

P09A7 Gate Select Position Circuit C Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Rationality fault on gate select circuit C: the value is electrically valid, yet it disagrees with the other select channels, the learned gate positions or the commanded movement. A Mannesmann Sachs patent shows why several select signals can exist: when one sensor fails, the remaining ones still allow controlled positioning before an emergency mode based on stored drive times takes over. No manufacturer documents this code or the role of circuit C publicly. CARB requires rationality checks on such inputs. P09A6, P09A8 and P09A9 are electrical faults of C, P0905 and P09A3 the same check on A and B. The driver usually notices slower or restricted shifting.

Likely causes

Drifting or worn sensor so signal C disagrees with the other channels
Select positions not relearned after repair work on the actuator or gearbox
Loose sensor mounting or magnet shifting the measured position
Contact resistance in the connector of circuit C

Symptoms

  • Check engine or transmission warning light on
  • Slower or hesitant gear changes
  • Some gears no longer offered

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 cwiring harnesstcm

Related codes

P09A6P09A8P09A9P0905P09A3P0909

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