I have a 2002 Expedition with a 4.6L. My Service Engine soon light has come on, I replaced the gas cap but it did not help. I unplugged the battery for about 30 seconds, but it did not help either. From what I have read it is probably the oxygen sensor, how easy is it to replace it(them)? And where are they located?

 

Take the SUV down to your local Autozone and get them to read the codes (its free). There are literally hundreds of codes and any number of them could be causing the SES.

 

Also, your SES light comes on when you have an emmissions problem. Your emmission warranty is longer than you regular warranty.

How many mile you got on your truck?

 

I agree with Ken and Ken. Find out the specific problem before you randomly start throwing money at possible culprits. To answer your question. There are four O2 sensors, two upstream and two downstream. This means a couple are before the cats and a couple after. They are inserted into the exhuast pipes and look kind of like sparkplugs.

 

Thanks..I have 27,000 miles, so it should be covered...
Thanks again.

 

I would take it to the dealer and have them fix whatever it is under warranty. This truck's too new for you to be throwing money at it.

If it's the O2 sensors, it's a huge PITA. I've almost finished my EOG article on replacing the O2 sensors.

XXL

 

Definately get the codes read. I believe most of your emmissions are covered til 80,000 miles or so. Since there is only 27,000, you should be good for about everything.

 

most emission parts are covered for 7 years or 80000 miles that includes your processor and conver. I don't like it covers egr system

 

I also had the service engine soon light come on but I was watching the milage turn 100000 and as it did the light activated is this a pre-programed light just to get you in the service center?

 

There's an extremely good chance that this is the case. Ford recommends the spark plugs be replaced at 100,000mi , which is a big-money job for them (-/+$350, $300+ of which is labor alone!). Try disconnecting your battery for 15 - 30 minutes - that will clear the codes out. If it's a legitimate problem, the light will come back on. Until then, don't worry about it - my dad drives around with those lights on all the time. His Mercedes has had the SERVICE light on for a couple years now - he just put black electrical tape over it. If you can't see it, it doesn't exist!

XXL