Mustang oxygen sensors can fail or become damaged over time causing your Malfunction Indicator Light (MIL) to turn on. Your 1994-04 Mustang's O2 sensors read the amount of oxygen in your exhaust to adjust air/fuel ratios. A malfunctioning sensor can cause lean and rich conditions while illuminating your check engine light. Fix yours today with a replacement sensor or extension harness to fit your application. Get your replacements today at Late Model Restoration. Upgrading to long tube headers? Pick up a set of Mustang 02 sensor extensions for an install done the right way. These sensors fit 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, and 2004 Mustangs.