P0821
Gear Lever X Position Sensor 1 Circuit
General electrical fault on the X-axis (left/right) position sensor 1 of an electronic gear lever. Used in stick-shift-by-wire systems where the lever is decoded into X/Y coordinates rather than discrete switches.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
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.
- Open or shorted wiringCommon
Parts involved
- Gear Lever X Sensor
- Wiring Harness
P0821 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.