How to Replace Driver side Upstream O2 Sensor 04-07 Cadillac CTS
Difficulty: Intermediate · About 75 min · Cadillac Cts
Replace the driver-side upstream oxygen sensor on a 2004–2007 Cadillac CTS, removing the cowl and wiper transmission to reach the sensor connector behind the engine.
Tools you will need
- Socket Extensions
- Torque Wrench
- 15mm Socket
- O2 Sensor Socket
- 7mm Socket
- Painter's Tape
- 10mm Socket
- Ratchet
Parts and supplies
- Driver-side upstream oxygen sensor
Steps
Mark and remove the wiper arm
Mark the blade's resting location on the windshield, remove the arm cap and retaining nut, and lift the arm from its splined pivot.
Remove the cowl and wiper transmission
Peel back the weather seal, remove the cowl fasteners, and lift the panels away. Unbolt and disconnect the wiper transmission to reach the rear of the engine.
Remove the engine cover
Remove the oil cap and lift off the engine cover, then replace the cap temporarily to keep debris out. Locate and unplug the driver-side upstream sensor.
Remove the old oxygen sensor
Free the sensor lead from its clips and use an oxygen-sensor socket to loosen the sensor from the exhaust. Remove it by hand once loose and compare it with the replacement.
Install the replacement sensor
Thread the new sensor into the exhaust by hand to prevent cross-threading, then tighten it to the vehicle's specification. Reconnect its plug and secure the lead in the original route.
Reinstall the cowl and wiper
Refit the engine cover, reconnect and bolt down the wiper transmission, then reinstall both cowl panels and the weather seal. Align the wiper arm to its mark and test operation.
Check your vehicle’s repair manual for exact specifications and fit.