Whether you are putting a LS1 into a 240SX, Miata or other donor vehicle, it’s handy to know how to change LS1 swap oxygen sensors. The GEN III and IV GM blocks so popular with engine swappers requires two oxygen sensors, and today we’ll be showing you how to replace your LS1 oxygen sensors in our 1996 Mazda Miata LS1 swap.
Before you begin our DIY article on how to change LS1 swap oxygen sensors, it’s a good idea to know what part numbers you’re going to be dealing with. Both LS1 oxygen sensors are different, and have their plugs oriented in a certain way so that it’s impossible to mix them up. You can of course switch and swap these sensors, if you make the proper corrections to the plugs in order for them to fit.
The GM part numbers for these two oxygen sensors are 25161131 and 25312197 for the left and right oxygen sensors respectively. These are for the upstream 02 sensors, meaning the primary oxygen sensors in your LS1 swap.
To begin, unplug your LS1 o2 sensor connectors and let the oxygen sensors hang from your headers. You do not need to undo or remove any exhaust components for this DIY article, unless they prevent you from somehow unscrewing the LS1 02 sensors.
Using a 02 sensor socket or open ended wrench, crack your LS1 oxygen sensors loose, and then gently remove.
Once your left and right oxygen sensors have been loosened, go ahead and unscrew them to remove. Open your new LS1 oxygen sensors up and if the manufacturer has supplied anti seize or similar material, go ahead and apply gently to your threads.
Make sure not to get any contaminant or anti seize on the oxygen sensor element. Keep the lubricant on the threads only and carefully screw back into your LS1 headers to complete this job.
Reconnect your 02 sensor wiring looms, and make sure to tighten both oxygen sensors to specification. Once you have reconnected your 02 sensors, you can opt to clear your OBDII trouble code, or simply reset your LS1 ECU to clear any codes that may have been stored in the system.
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