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Spark Plugs Guide & Diagnostic Information

Spark plugs ignite the compressed fuel-air mixture in the engine combustion chambers.

Location on Vehicle

Screwed into the top of the cylinder heads inside the combustion chambers.

Typical Symptoms of Failure

  • Misfiring when cold
  • Engine shaking at idle
  • Decreased gas mileage

Associated Diagnostic Trouble Codes

A malfunction in the Spark Plugs can trigger the following OBD-II fault codes:

Estimated Replacement Cost

Typical cost to replace the Spark Plugs: $80 - $250 for a full set (parts and labor).

Citations & Authority References

This technical part definition is cross-referenced with:

  • EPA On-Board Diagnostics II Standard Specifications
  • SAE J2012 Automotive Component Design Regulations

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