P0959
Auto Shift Manual Mode Circuit Intermittent
The auto-shift manual mode circuit reports a intermittent condition. Manual mode shift requests cannot be reliably interpreted.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: easy
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.
- Connector not seatedCommon
- Noisy ground referencePossible
- Connector with intermittent contact under vibrationLess likely
Parts involved
- Auto Shift Manual Switch
- Wiring Harness
- TCM
P0959 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.