Ignition System - SES Lamp ON/DTC P0300 Set/Misfire

TSB SB04-01-S002
Service Engine Soon/Check Engine Light
Illuminated, Misfire or Roughness, DTC
P0300 Set (Replace Spark Plugs)

Light Duty ASCENDER 2003 Bulletin Engine 06/01/04

Service Engine Soon/Check Engine Light Illuminated, Misfire or Roughness, DTC P0300 Set (Replace Spark Plugs)

ISSUE DATE: JUNE 2004

Affected Vehicles





2003-2004 Isuzu Ascender (US/UT) models equipped with 4.2L engines (RPO: LL8) built within the VIN breakpoints shown.

Service Information
Condition:
Some owners may comment on engine roughness, misfire or illumination of the Service Engine Soon/Check Engine Light.

Possible Cause:
Upon investigation, the technician will find a DTC P0300, some of these vehicles may have been built with spark plugs that misfire. If a spark plug misfires, it could result in illumination of the Service Engine Soon Light/Check Engine Light and/or engine misfire and roughness.

Correction:
Use P0300 diagnostics in the Service Manual to identify the source of the concern. If the concern is determined to be a spark plug, replace the spark plug and inspect for date code.

NOTE:
There will be a 6-digit number stamped on the spark plug. The first 3 digits are the date code.

Service Procedure





Inspect the spark plug for a date code (see figure 1).

203 = Date Code

3 = Year

1 = Line

1 = Shift

^ If the date code on the spark plug is 154, 155, or 156, REPLACE ALL OF THE SPARK PLUGS.





^ If the date code on the spark plug is NOT 154, 155, or 156, replace only the spark plugs indicated by diagnostics.





Parts Information

Warranty Claim Information





Use the labor operation shown.





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