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How to Replace Passenger Upstream O2 Sensor 03-07 Cadillac CTS

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  1. step : Removing the Wiper Arm (0:48)
    • Pry off the wiper arm cap by hand
    • Remove the 15mm nut from the wiper arm stud
    • Pull the wiper arm off the stud
  2. step : Removing the Cowl Panel (1:59)
    • Peel off the weatherstrip
    • Remove the four 7mm screws from the cowl panel
    • Lift up and carefully release the passenger side of the cowl panel
    • Remove the 10mm nut from the driver side cowl panel
    • Remove the driver side cowl panel up and out
  3. step : Removing the Wiper Transmission (2:57)
    • Remove the two 10mm bolts from the wiper transmission assembly
    • Lift the assembly up toward the center of the vehicle
    • Disconnect the transmission wiring harness
  4. step : Removing the Engine Cover (3:33)
    • Remove the oil fill cap
    • Remove the engine cover
    • Reinstall the oil cap
  5. step : Removing the Passenger Upstream O2 Sensor (3:57)
    • Remove the three 10mm bolts from cowl panel retainer connected to the firewall
    • Disconnect the O2 sensor connector on the backside of the engine
    • Loosen the O2 sensor with a sensor socket or a 22mm socket
    • Remove the sensor by hand
  6. step : Installing the Upstream O2 Sensor (6:58)
    • Install the O2 sensor by hand
    • Tighten the O2 sensor with an O2 sensor socket of 22mm socket
    • Connect the wiring harness
    • Insert the cowl panel retainer into place
    • Tighten the three 10mm bolts to the cowl panel retainer
  7. step : Installing the Engine Cover (7:55)
    • Remove the oil fill cap
    • Press on the engine cover
    • Reinstall the oil cap
  8. step : Reinstalling the Wiper Transmission (7:56)
    • Connect the wiper transmission electrical connector
    • Insert the wiper transmission into place
    • Tighten the two 10mm bolts to the wiper transmission
  9. step : Reinstalling the Cowl Panel (8:24)
    • Insert the driver side cowl panel into place
    • Tighten the 10mm nut to the driver side
    • Insert the passenger side cowl panel into place
    • Tighten the 7mm screws to the panel
    • Press on the weatherstrip
  10. step : Installing the Wiper Arm (9:42)
    • Put the wiper arm onto the stud
    • Fasten the 15mm nut onto the wiper arm stud
    • Push on the wiper arm cap

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Hi, I'm Mike from 1A Auto. I hope this how-to video helps you out, and next time you need parts for your vehicle, think of Thanks!

In this video, we're going to be working with our 2006 Cadillac CTS 2.8-liter V6. We're going to be replacing our bank 1 sensor 1 O2 sensor. This is the upstream passenger side on this particular vehicle. If you like this information, please click the subscribe button. We have a ton more information on this vehicle, as well as many other makes and models. If you want these parts for your car, you can follow the link in the description.

Here are the items you'll need for this repair: 7mm, 10mm, 15mm socket, ratchet, socket extension, O2 sensor socket, torque wrench, and painter’s tape.

Remove the black caps over the nuts for the windshield wiper arms. All you have to do is squeeze them together. Pop them off. We're going to use a small piece of painter's tape. You should use the straight edge to mark the position and angle of the wiper blade, so we can reinstall our wiper arms properly. Remove the two 15 millimeter nuts, securing the wiper arms down with 15 millimeter socket and ratchet. Work the wiper arms off of the splines. Do this by grabbing them at the joint, simply pulling up and pushing down. Eventually, it'll work its way off the splines, and you can remove your wiper arm.

Peel off the leather strip. Move these four 7 millimeter screws. We're going to use a 7 millimeter socket and ratchet. Lift up, carefully release this plastic, as it's hooked under the windshield. See the little hooks here, just be careful to pull out and away with those. Remove this 10 millimeter nut up against the fender on the driver's side. Lift up off of the splines for the wiper arms. Remove the driver's side of the cowl cover.

Remove these two 10 millimeter bolts securing the wiper transmission and assembly into the vehicle. It's a little easier to access this top one from the other side of the hood. We're going to use a 10 millimeter socket, ratchet, and extension. Lift up and toward the center of the vehicle to release this tab. Flip over the assembly. Release the connector. Remove the assembly from your vehicle.

We're going to remove the engine cover to make it easier to gain access to the backside of the engine, and because I'm going to have to lay across the intake to get back there. We don't want to risk breaking the plastic. Remove the oil cap. Lift up and pop off the cover. Reinstall the oil cap to prevent any dirt and debris from falling in while we're working.

To access the passenger side O2 sensor connector, remove these three 10mm bolts. Should be able to remove this plastic cover and reach down the backside of the engine. After you've removed the last bolt, pull out and up to remove the cover from under the cowl. Pop the connector off of this clip. Release the connector and pull them apart.

Install an O2 sensor socket or a 22mm wrench over the O2 sensor. Crack it loose, and then you should be able to remove it the rest of the way by hand. Be sure that the connector and the sensor wires aren't hung up on anything that's going to cause them to twist or potentially break while we remove the sensor. Remove it from the vehicle.

Here we have the two upstream O2 sensors that we removed from our 2006 Cadillac CTS 2.8-liter V6 and our new part from As you can see, both old sensors are identical to each other as well as the new sensor. The same 22mm hex, same threads, same tip on them. The new one comes coated in an anti-seize lubricant to prevent it from locking into the exhaust after you install it. We have the same length wires wrapped in a heat-treated coating to keep them from melting, being along the back of the engine and the exhaust. The connectors themselves are the same on all three components. The new one actually comes with a new clip.

Sometimes these break off or get stuck in the motor. Ours are stuck in the engine, so if we want, we can simply pop that off, lock it back into the connectors that are already there or we can pry these out of the motor. Have a nice fresh tab to hold this in place. Faulty oxygen sensors can be the cause of rough running conditions, lean or rich engine codes as well as being partially responsible for the PO420 catalytic converter codes that are common on a lot of vehicles. If you've narrowed down that the upstream O2 sensor is the cause of any of these issues for you, this new part from 1AAuto is going to go in direct fit just like your original equipment and fix you up right.

Reinstall your O2 sensor. Bring it down as much as you can by hand. Finish installing with an O2 sensor socket and ratchet or a 22mm wrench. Remove the O2 sensor socket and send the sensor wire back up behind the motor so we can reconnect it at the top.

Reconnect the electrical connector. Snap the safety into place. Mark the connector back onto its retainer. Reinstall the driver's side of the cowl cover first. Be sure that all the plastic hooks line up under the windshield. Reinstall the 10 millimeter nut. Reinstall the passenger side of the cowl cover. Again, make sure that all these hooks line up and go underneath the windshield. Reinstall your 7 millimeter screws. Reinstall the rubber seal, the channel simply presses onto this ridge here.

Line up your wiper to the tape mark we made on the windshield earlier. Torque to 26 foot-pounds. Line up your wiper to the tape mark we made earlier. Start the nut by hand. Torque the nut to 26 foot-pounds. Reinstall the plastic cap. Close the hood, remove the tape marks from the windshield. Check for proper operation of your wiper motor.

Thanks for tuning in. We hope this video helped you out. Next time you need parts for your car, please visit Also check out our other helpful how-to and diagnosis videos.

Tools needed for replacement:

    Materials, Fluids, and Supplies

  • Painter's Tape

  • Ratchets & Related

  • Torque Wrench
  • Socket Extensions

  • Sockets - Metric

  • 7mm Socket
  • 10mm Socket
  • 15mm Socket

  • Specialty Tools

  • O2 Sensor Socket

2005 - 2005  Cadillac  CTS
2004 - 2005  Cadillac  CTS
2006 - 2007  Cadillac  CTS
2005 - 2005  Cadillac  SRX
2006 - 2006  Cadillac  SRX
2005 - 2005  Cadillac  STS
2006 - 2007  Cadillac  STS

03-07 CTS w/2.8L; 05-06 SRX; 05-07 STS w/3.6L; 06-09 STS w/4.6L Upstream Oval Con O2 Sens LF=RF (AC)

Cadillac CTS SRX STS Driver or Passenger Side O2 Oxygen Sensor ACDelco 213-3240

This part replaces:

  • AC Delco 213-3240
  • OE # 12596327

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