These O2 sensor extension harnesses are sold in a pair of TWO.
They are used to relocate the front 02 Sensors (AFR) from the stock location to a new location like into the collector of the Thorley Long Tube Headers.
The latest version of the Thorley Long Tube Headers for the Toyota 4.0L V6 1GR-FE engine now has an O2 sensor bung located in the header collector. This will allow the sensor to sample the exhaust gas from all of the cylinders on that side of the engine instead of just the center cylinder. To relocate the sensor to the collector these extension harnesses are needed because the stock harness is not long enough.
Fits all the Toyota 1GR-FE engines, 2005 and later. Does not fit the 2003-2004 4Runner 1GR-FE engine. Does not fit the rear O2 sensor connectors.