Ignition
Spark Plug
The spark plug ignites the compressed air-fuel mixture at the right moment.
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Ignition flow
Interactive — tap a partTap a part to see how it fits in the system.
What it does
- Delivers high-voltage spark across the electrode gap
- Ignites the mixture for combustion
- Cools the combustion chamber slightly
When it fails
- Misfire and rough idle
- P0300–P0304 codes
- Poor fuel economy
- Hesitation under load
How to diagnose
- Read the OBD codes first
- Inspect the electrode color and gap
- Swap plugs between cylinders to isolate
Maintenance
- Replace per the manual (20k–100k km by type)
- Gap the plugs correctly
- Replace the whole set together
Use the diagnosis order. When a part fails, confirm each hypothesis with measurements before replacing anything — codes and symptoms overlap.
Related part
Ignition Coil
The ignition coil transforms battery voltage into the tens of thousands of volts needed for the spark.