P0300
Category: Powertrain
Urgency:
Critical Severity
P0300: Random / Multiple Cylinder Misfire Detected
Code P0300 indicates that your vehicle engine control module (ECM) has detected that multiple cylinders are misfiring randomly, which can damage the catalytic converter.
Common Symptoms of P0300
- • Flashing or solid Check Engine Light
- • Engine hesitation or stumbling during acceleration
- • Rough idle and engine vibration
- • Strong gasoline smell from exhaust
- • Significant loss of fuel economy
Root Causes for Code P0300
- • Worn out or fouled spark plugs and plug wires
- • Faulty ignition coils or coil packs
- • Vacuum leak in intake manifold or hoses
- • Clogged or defective fuel injectors
- • Low fuel pressure or failing fuel pump
Step-by-Step DIY Diagnostic & Inspection Guide
1
Inspect and replace old spark plugs and ignition coil boots.
2
Check for cracked vacuum hoses or hissing sounds around the intake.
3
Test fuel pressure with a mechanical gauge.
4
Perform an engine compression test if misfires persist across specific cylinders.
Estimated Repair Costs
Replacement Parts:
$40 - $180
Shop Diagnostic / Labor:
$80 - $220
Total Estimated Cost:
$120 - $400
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