OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

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.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number8 / 04

Possible causes

  • Open or shorted lamp wire high
  • Failed lamp bulb or LED 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

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 40–200 €
  • Estimated time: 0.2–1 h
  • Component: skip shift lamp
  • Component: wiring harness
  • MIL / check engine light

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication