2016 Mazda 5 GS, Automatic TransFACTORY OEM SERVICE PROCEDURE

No. 29 Spark Plug Condition: Notes

NO. 29 SPARK PLUG CONDITION DESCRIPTION AND POSSIBLE CAUSE

29 SPARK PLUG CONDITION
DESCRIPTION
  • Incorrect spark plug condition.
POSSIBLE CAUSE
NOTE:
  • Inspecting the spark plug conditions can determine whether a problem is related to a specific cylinder or possibly all cylinders.
Wet/carbon stuck on specific plug:
  • Spark-Weak, not visible
  • Air/fuel mixture-Excessive fuel injection volume
  • Compression-No compression, low compression
  • Malfunction spark plug
Grayish white with specific plug:
  • Air/fuel mixture-Insufficient fuel injection volume
  • Malfunction spark plug
Wet/carbon is stuck on all plugs:
  • Spark-Spark weak
  • Air/fuel mixture-Too rich, excessive fuel line pressure
  • Erratic signal to PCM
  • ECT sensor or related circuit malfunction
  • MAF sensor or related circuit malfunction
  • A/F sensor or related circuit malfunction
    • HO2S or related circuit malfunction
  • Compression-Low compression
  • Restriction in intake/exhaust system
Grayish white with all plugs:
  • Air/fuel mixture-Too lean, insufficient fuel line pressure
    WARNING:
    • The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before servicing the fuel system:
  • Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel.
    • Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this service information. (See BEFORE SERVICE PRECAUTION .) (See AFTER SERVICE PRECAUTION .)
    CAUTION:
    • Disconnecting/connecting the quick release connector without cleaning it may cause damage to the fuel pipe and the quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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