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

P0300

Random/Multiple Cylinder Misfire Detected

The ECU has detected misfires that are not concentrated on a single cylinder. The misfire monitor measures crankshaft acceleration after each combustion event; missing acceleration on multiple cylinders, or randomly across cylinders, triggers this code.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number3 / 00

Possible causes

  • Worn spark plugs high
  • Vacuum leak affecting all cylinders high
  • Fuel pressure low medium
  • Timing chain stretched (high mileage) low

Symptoms

  • Check engine light on or flashing
  • Rough idle and uneven running
  • Power loss, hesitation under acceleration
  • Increased fuel consumption
  • Possible smell of unburned fuel from exhaust

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 50–1500 €
  • Estimated time: 0.5–6 h
  • Component: ignition coil
  • Component: spark plug
  • Component: fuel injector
  • Component: intake manifold
  • Component: timing chain
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required
  • limp mode possible

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