P0803
Upshift/Skip Shift Solenoid Control Circuit
General electrical fault on the upshift/skip-shift solenoid control circuit — used on manual-transmission performance vehicles to force a skip from 1st straight to 4th under low-load cruise (CAFE fuel-economy feature). With the input invalid the lockout cannot be applied.
- 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 control wireCommon
Parts involved
- Skip Shift Solenoid
- Wiring Harness
P0803 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.