I have a 2002 6 cyl Mercury Cougar. I need to replace the o2 sensor... How would I do that?

you can have a stuck or bend valve in cylinder 3

If it is a 7.5 amp fuse, it powers the charge warning light in the cluster and applies voltage to the alternator to make it charge.
You will need someone to trace that circuit and look for a short to ground. It may be in the cluster or in the harness.
Something else besides the fuse is making the car not start.

In most cases if the timing is off the car wont start, have you checked the O2 sensors. I had a truck with a similar problem and O2 sensors fixed it for me. Hope it helps.

Almost all O2 Sensors ever installed in any vehicle are in
both ends of the exhaust converter

On some older vehicles from the 1980's the first one was
in the pipe before the converter
On some newer asian vehicle,in the exhaust manifold close
to the engine

You have wires to follow,so it is an easy find


If you got an O2 Sensor Code,you DO NOT REPLACE
it. A code has nothing to do with the sensor in that respect

All codes only indicate a possible system malfunction and
diagnostic testing is required

Not saying your sensor isn't slow to swing from .02volts to .08 volts
and may need to be replaced. Throwing parts at things gets expensive

Education is the key. If you do not know your vehicle systems or
OBD2 in general,you may want to leave the hood closed

At minimum it has a least two.Depending on which engine is in it 4 cyl or 6 cyl it may have 4 with the 6 cylinder.

you might not believe this but you have to remove the right axle to get the alternator out.

Valdi

could be ur o2 sensors or clogged catalytic converter these have a lot to do with emmission sometimes its a bad gas cap number one problem evap get a new one and check code again the cap has a seal that if it leaks gives you evap code

might be number one fuel injector not letting enough gas enter the # 1 cylinder.

I just got done replacing the O2 sensors in my 99 Cougar due to throwing a P0135 malfunction code. There's 3. Facing the engine there's one in the front coming off of the front header, which is easy to get to. Another more tricky one if between the engine and the fire wall on the rear header pipe. The third is under the vehicle behind the transmission pan on top of the exhaust. In order to replace the O2 sensor near the fire wall you will need to remove the 4 retaining bolts for the ECM module and move it out of the way. Additionally you will need to remove the 2 retaining nuts for a wiring harness that is seated below the ECM module. Pay close attention to the connectors because the front and under vehicle O2 sensors have round connectors the one near the firewall has a squared connector. I was able to replace all 3 by myself in approximately 35 minutes. If your throwing a O2 heater malfunction code it is most likely going to be the sensor near the firewall. make sure that you know someone with a code reader so the code can be cleared. If you're do for an emmissions inspection be sure to put at least 40 miles on the new O2 sensor with different types of driving (e.g. highway, coasting, decellerated turns and rapid acceleration). Gotta love project cars for your kids!!

there is a fuse for the o2 heaters if one of the sensors blew the fuse they will all be out