How do you replace the oxygen sensors on the 1998 ford mustang cobra?

Answer 1

Sneighke answered:The '96-on DOHC 4.6l engines have a total of FOUR O2 sensors (prior engines having only two). Each set of two have similar, but very different functions and are of different models.

The "front" set are ahead of the 4 catalytic assemblies toward the engine and are the fuel mixture feedback sensors. These are the most important as they directly control the EEC fuel feedback and tell the system how to tune the fuel mixture the best depending on operating conditions.

The "rear" pair are located behind the second set of cats and do not affect fuel control. Their purpose is to simply monitor the final exhaust and determine if excess fuel, beyond allowable transient conditions, exceed amounts which would indicate catalytic converter failure to the EEC-V emission control system. If they either detect excessive fuel, or are bad (rare), they will cause a check engine code and cause a check engine light. Likewise, the front sensors can do the same if either they are bad (rare), or if there is a fuel delivery issue, or any other condition affecting fuel delivery such as a vacuum leak, or possibly any modification to the induction system which upsets the system beyond what the EEC is programmed to consider normal and proper.

Note that if the EEC-V does cause a check engine light, it will also store a code indicating which of the four sensors it deems defective. A "code reader" or your dealer can read the codes in seconds.

In general the O2 sensors last a long time unless a (typically) mechanical problem exists, in most cases, excessive oil consumption due to engine wear, or possibly incorrect modification. This would almost always eventually result in one or both of a sensor or catalytic converter failure either of which will cause a system error code.

As far as replacing them, it's pretty simple. Gently unplug the sensor, and use the proper socket wrench to remove from the exhaust system.

IMPORTANT--- The front and rear sensors are NOT the same model and must be replaced with the same model.

Once the new ones are reinstalled and tightened to the required torque, the cables are just plugged back in.

FYI, it is possible to easily bench test the sensors, but it has to be done properly and carefully and such information is easily found on car enthuseist sites and is beyond the scope of this question.