P0909
Gate Select Control Error
The TCM detects that the gate select actuator does not reach the commanded position within tolerance. Mechanical bind, weak actuator, or sensor offset.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Common causes
Ordered by how often each turns out to be the cause.
- Selector mechanism bindingCommon
- Actuator force degradedPossible
Parts involved
- Gate Select Actuator
- Gate Select Position Sensor
- TCM
P0909 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.