P0804
Upshift/Skip Shift Lamp Control Circuit
General electrical fault on the upshift/skip-shift indicator lamp control circuit — the dashboard light that prompts the driver to skip from 1st straight to 4th. With the input invalid the lamp cannot be illuminated.
- 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.
- Open or shorted lamp wireCommon
- Failed lamp bulb or LEDPossible
Parts involved
- Skip Shift Lamp
- Wiring Harness
P0804 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.