High Safety risk Emissions Powertrain-code

P0300

Random/Multiple Cylinder Misfire Detected

Indicates that the engine control module (ECM) has detected misfires in multiple cylinders or cannot identify a specific cylinder, often due to issues in the ignition, fuel, or engine systems. Can lead to reduced performance, increased emissions, and potential engine damage if severe.

Pull over safely and book service immediately

This code is flagged as a safety risk. Avoid driving until a technician has inspected the vehicle.

Symptoms

  • Engine stumbles or hesitates
  • Illuminated check engine light
  • Lack of power
  • Poor fuel economy
  • Rough idle
  • Vibration during acceleration
  • Increased exhaust emissions

Likely causes

  • Faulty spark plugs or ignition coils
  • Worn or fouled spark plug wires
  • Vacuum leaks (e.g., intake manifold gasket)
  • Low fuel pressure (e.g., failing fuel pump or clogged fuel filter)
  • Faulty oxygen sensors or mass air flow sensor
  • Head gasket failure
  • Valve cover gasket leaks causing oil contamination
  • Improper valve timing or adjustment
  • Engine mechanical issues (e.g., low compression, worn piston rings)

Repair approach

  1. 1 Inspect and replace spark plugs
  2. 2 Check and replace ignition coils
  3. 3 Inspect valve cover gasket for leaks
  4. 4 Test fuel system pressure
  5. 5 Check intake manifold gasket for vacuum leaks
  6. 6 Diagnose head gasket or engine compression issues
  7. 7 Verify valve adjustment
  8. 8 Use OBD-II scanner to confirm misfire codes (P0301–P0312 for specific cylinders)
Labor estimate
3h typical
Range: 1h – 8h
Parts cost
$50 – $2,000
Range varies by year/make/model

Related codes

P0301 — P0301 Cylinder #1 MisfireP0303 — P0303 Cylinder #3 MisfireP0304 — P0304 Cylinder #4 MisfireP0305 — P0305 Cylinder #5 MisfireP0307 — P0307 Cylinder #7 MisfireP0308 — P0308 Cylinder #8 MisfireP0309 — P0309 Cylinder #9 MisfireP0310 — P0310 Cylinder #10 MisfireP0311 — P0311 Cylinder #11 MisfireP0312 — P0312 Cylinder #12 Misfire

Information shown is reference-grade and may vary by vehicle. Always have a qualified technician confirm the cause before any repair.