GM 12571533
Spark Plug

Starting the procedure requires turning off the Ignition Switch followed by removing the Ignition Coil assemblies. Keep the engine temperature low while you wait to remove spark plugs so the plug threads do not seize against Cylinder Head threads. Use a thread chaser as a cleaning tool (Tool Required: Thread Chaser) to remove any foreign elements in the Spark Plug recess area before the new plug installation to avoid thread contamination and improper seating. Motorists must first eliminate engine spark plugs before conducting inspection. The vehicle requires exactly the stated spark plugs because other temperature options will damage the engine significantly. All new and reconditioned spark plugs require round feeler gage testing for accuracy before installing because handling may have modified their pre-set gaps; check every plug gap and compare them to specifications then adjust as needed. The Cylinder Head has smooth threads for the Spark Plug which must be fully inserted into position using a thread chaser for cleaning the threads if needed. Fasten the spark plugs onto the engine while tightening them to 15 n.m (11 lb ft) before reinstalling the Ignition Coil assemblies.

Install the spark plugs into the engine, ensuring the threads engage smoothly and the plugs are fully seated; use a thread chaser if necessary to clean the threads.

Turn OFF the ignition switch and remove the ignition coil assemblies for both Bank 1 and Bank 2.

Check the gap of all new and reconditioned spark plugs with a round feeler gauge, as pre-set gaps may change during handling.

Ensure the threads engage smoothly and the plugs are fully seated.