It is a 3.1 Liter V6, so it has 6 spark plugs.
A/C Delco #41-103, these will idle better than other brands. Also good, NGK, or Denso, stay away from Bosch, and any platinum plugs.
They are in the sides of the head where the exhaust manifolds are.
Change the spark plugs at 100,000 miles. 03 still has a serviceable fuel filter and that can be changed too. For all the answers about these trucks join our enthusiasts forum at www.trailvoy.com
A 2003 Chevy Suburban will crank but not start if it has no spark or fuel. Checking for a clogged fuel filter or fouled spark plugs can help to resolve the problem.
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They will normally last at least 75,000 + miles. Check your owners manual.
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