I have a 1996 GT. I was wondering if the there is a need to have a heated oxygen sensor. Are our stock sensors heated ? (2, 3 or 4 wires?).

Thanks,
James

 

The 1996-2004 GTs have four heated O2 (HEGO, Heated Exhaust Gas Oxygen) sensors, two before the catalytic converters and two downstream of the converters--they are 4-wire devices.



While it's not technically necessary that they be heated sensors, the use of heated sensors speeds up their reaching operating temperature (1000°F), and ensures that the temperature stays at least that--making the sensor's output much more stable.

Note that replacing the OEM sensors with non-heated units will cause a DTC, and light up the Service Engine Soon lamp, as the PCM monitors the heater circuits.

The two before the cats are needed for proper engine operation, the two after the cats are used on for monitoring the efficiency of the cats--however their failure or removal will also cause the PCM to throw a DTC.