How to Replace Spark Plugs 05-08 Chrysler 300

Difficulty: Intermediate · About 105 min · Chrysler 300

Replace spark plugs on a 2005–2008 Chrysler 300, removing the upper intake plenum for access and protecting open intake ports from debris.

Steps

1. Replace the accessible ignition coils and plugs

   With the engine cool, unplug the ignition coils for the first accessible cylinders and remove their fasteners. Lift out the coils, remove the plugs, and inspect them for unusual wear.

2. Remove the upper intake manifold

   Disconnect the intake duct, sensors, vacuum lines, and harness retainers. Remove the manifold fasteners and lift the plenum clear, covering every open intake port with clean material.

3. Replace the remaining spark plugs

   Disconnect the remaining coils and remove their fasteners. Use a spark-plug socket to remove each plug, then thread the correct replacements by hand before tightening to the manufacturer's specification.

4. Reinstall coils and intake gaskets

   Refit the ignition coils and reconnect their wiring. Remove the port covers, clean the manifold sealing faces, and install new gaskets and seals wherever the originals were disturbed.

5. Reinstall the intake plenum

   Set the plenum in place without pinching wiring or hoses. Start the bolts by hand and tighten in the specified sequence and torque, then reconnect every vacuum line and electrical connector.

6. Start and check the engine

   Reconnect the intake duct and verify all clamps are tight. Start the engine and listen for vacuum leaks or misfires, then scan for diagnostic codes if the warning light appears.

Check your vehicle’s repair manual for exact specifications and fit.