How To Change your Cadillac ATS Oxygen Sensor

How To Change your Cadillac ATS Oxygen Sensor


The primary oxygen sensor in your Cadillac acts like your ECU or PCM’s “eyes” as it monitors the exhaust gases that are expelled from your 3.6 liter LFX V6 engine. Today we’ll be showing you how to change your Cadillac ATS Oxygen Sensor to resolve any DTC OBDII trouble codes.

This error can cause your Malfunction Indicator Lamp (MIL) to go off, signifying some sort of error with your 02 sensor or your ECU. The most common OBDII trouble code for this error is P0171, check here for how to replace the MAF sensor in your Cadillac ATS.

When it comes to the oxygen sensors in your ATS, there’s a primary downstream 02 sensor and the secondary 02 sensor. Both can have problems and encounter errors after some time, so it’s important to recognize what code your ATS is spitting out and what the location is for each 02 sensor.


Bank 1 and Bank 2 signify the left and right side of the engines, in this case it’s a V6 so there’s the left bank and the right bank. Sensor 1 and Sensor 2 signify the front or rear oxygen sensor, so make sure to check your DTC Trouble code for location details.

If you’ve got a OBDII trouble code for your Cadillac, there’s one of two reasons for your oxygen sensors to be having this problem. Either your 02 sensor has failed or died, or a less likely cause is there’s something wrong with your wiring. Today’s test vehicle is a 2014 Cadillac ATS with the v6 LFX engine, and today we’ll be replacing Bank 1 Sensor 1, which is the left bank primary 02 sensor.

Knowing how to change your Cadillac ATS Oxygen Sensor will save you a few bucks, especially because Sensor 1 / Bank 1 is very easy to access. To begin our how to change your Cadillac ATS Oxygen Sensor guide, open your hood and disconnect the negative terminal on your battery.


To locate your Cadillac ATS oxygen sensor, take a look at the exhaust manifold located on either side of your V6 LFX engine. Because we are dealing with Bank 1, you will be replacing the driver side 02 sensor and replacing it. The part number for this 02 sensor carries a GM part number of 12590035, as well as part numbers 12596688 and 12597449.


Before you start our how to change your Cadillac ATS Oxygen Sensor Guide, you’ve got to locate your 02 sensor and unplug the engine harness. The harness is mounted to a metal tab beneath the LFX V6 engine PCV ports and hoses.


Grab this connector and pull away from the metal tab to pull out the plastic retaining clip and free the plugs. Now with this oxygen sensor harness freed from the metal tab, depress the locking pin and unplug the GM oxygen sensor.


Now with this tab removed and unplugged, you are good to start removing your factory 02 sensor. Using a oxygen sensor socket, slide it over the sensor mounted inside of your exhaust headers.


If your primary 02 sensor is the culprit, the chances of your LFX engine running lean during closed loop operation is high. Always service and replace your upstream 02 sensors immediately as to prevent any long term damage to your engine.

Carefully unscrew the 02 sensor and remove the unit from your headers, and then apply anti-seize lubricant onto the THREADS of your oxygen sensor ONLY. Do not get any of the anti seize or any material in that fact to touch the oxygen sensor, as it may contaminate your sensors and threaten your reading integrity.

Make sure to tighten to specification and you’ve now successfully learned how to change your Cadillac ATS Oxygen Sensor. Congratulations!

Have any questions or comments about our Guide? Leave them below and let us know!