How to Replace Spark Plugs 03-07 Cadillac CTS
Difficulty: Advanced · About 150 min · Cadillac Cts
Replace the spark plugs on a 2003–2007 Cadillac CTS by removing the wiper cowl and intake plenum for access, then reinstalling new gaskets and checking for intake leaks or warning lights. Verify the engine configuration before ordering parts.
Tools you will need
- 13mm Socket
- Torque Wrench
- 15mm Socket
- 18mm Socket
- 10mm Wrench
- 5/8 Inch Spark Plug Socket
- Flat Blade Screwdriver
- 7mm Socket
- 10mm Socket
- Ratchet
Parts and supplies
- Spark plugs
- Intake manifold gaskets
- Ignition coils
Steps
Mark and remove the wiper arms
With the ignition off, mark each wiper's parked position on the glass. Remove the arm nuts and carefully release the arms from their splines without levering against the windshield.
Remove the cowl and wiper transmission
Remove the weatherstrip and cowl fasteners, then lift the panels clear. Disconnect the wiper transmission wiring and remove its mounting fasteners so the intake plenum area is accessible.
Remove the intake plenum
Remove the engine cover and disconnect the intake duct, throttle connector, vacuum lines, and harness retainers. Label connections as needed, remove the plenum fasteners and brackets, then lift the plenum away without damaging its mating surface.
Replace the spark plugs
Disconnect each ignition coil and remove its retaining fastener. Lift the coil out, remove the plug with a spark plug socket, and install the correct new plug by hand before tightening it to the engine specification. Repeat for each cylinder.
Reinstall coils and plenum
Reinstall each coil in its original position and reconnect its electrical plug. Remove old plenum seals, clean the mating surfaces, fit new gaskets, and reinstall the plenum using the specified tightening sequence and torque.
Restore intake connections
Reconnect the vacuum hoses, throttle wiring, harness retainers, brackets, intake duct, and engine cover. Check every connector and hose for a secure fit before starting the engine.
Reinstall the cowl and wipers
Reconnect and secure the wiper transmission, refit the cowl panels and weatherstrip, then align the wiper arms with the marks made earlier. Tighten their fasteners to specification and test the wipers through a full cycle.
Check engine operation
Start the engine and listen for intake leaks or misfires. Confirm no warning lights appear, check that all tools are clear of the engine bay, and verify the wipers park correctly.
Check your vehicle’s repair manual for exact specifications and fit.