How many are there?

[Phatt_daddy]

I have talked to my local dealer service and I posed this question..... How many o2 sensors should I have on my '98 with a build date of 9-'97? They said 4. Then I asked the parts counter about a wiring harness that contains the plugs for the sensors and told them what I was looking at under my car and they said that I may have a '97 wiring harness and that only takes 2 o2 sensors. Who is right and what do I do if I need four but can only find the plugs for two? Oh and btw the two I have are before the cats and I am running no cats either.

Nate

 

[RandyStinchcomb]

there are ONLY 2 Oxygen sensors and they are in front of the cats.
then aft of the cats are 2 Oxygen monitors but all they do is measure how efficiently the cats are working.

 

[Phatt_daddy]

Let me clarify then..... One dept told me that either i place a factory style exhaust back on the car or get a set of MIL eliminators and the other dept said that I need nothing but to replace the two that Ihave now. All this to get rid of the check engine light and the bogging from it loading up with fuel.

Nate

 

[RandyStinchcomb]

if you dont have cats, you dont need the monitors working, either get MIL delete, which only seem to work 1/2 the time or have them turned off inna' tune.
when it comes to the O2's, get OEM Ford ones but your problems wth the engine "loading-up" wth fuel may not be from bad O2's, how many miles on them and why do you need the harness for them?

 

[5spd GT]

Your car will have 4 total 02 'sensors'. The first two are the actual sensors, and the back two are 02 monitors.

Many of the parts store (like Bosch) 02 sensors, work as a sensor or monitor. I have had no issues with mine.

However, if you can get a good deal on some OEM sensors and monitors, go for them

 

[Phatt_daddy]

Well when I was under the car I started looking for a set eliminators and got to noticing that I only had two plugs under the car let alone going to the exhaust. Those two plugs are for the sensors in which only one is plugged in with the plastic connector on the sensor gone for the other. I was checking on the harness just in case the idiot I got the car from hacked off the other two plugs (the ones that the elims connect to). That was when the parts counter told me that with my build date being 09-97 that I could possibly be running just the two instead of the four. As for mileage the car has 107355K and I assume it is on the factory o2s.

Nate

 

[5spd GT]

The parts counter guy was wrong.

The front two are sensors, and the back two are the monitors. The back two are the ones that the malfunction indicator light eliminators are for.