My checked engine light turned on today. I pulled code 41. It says, EGO sensor voltage signal always lean-does not switch. I replaced my o2 sensor a year ago. Could it be bad already?

 

Not necessarily. Something else could be causing your engine to run lean. That's the problem with computerization. Nothing is as it seems. Sometimes it pays to have a mechanic do the troubleshooting for you.

 

The 02 sensor code seems to pop up a lot for no reason. As long as my truck is running properly and passes smog, I ignore it. The light hasn't come on for a long time now, but I can recall a couple of years ago when it came on a lot, and it used to come on at the same time in my morning drive every day. Went through three different 02 sensors and finally installed the Ford factory one and it went away. But every now and again the light will come on randomly, so I just turn the truck off and restart it and it goes away and doesn't come back. The way I figure that is that must not have been very important!

Also I once read something about the light being programmed to come on at certain mileages for some reason or another, but there is nothing wrong. They just wanted people to take them into the shop for a checkup or something.

 

Ya, I know, but it just bothers the heck out of me becuase I can not stand looking at it. Jbronco, my symptoms are just like that. After about 15 min. of driving it will pop on, but once I turn my truck off and restart it, it is gone all the sudden. I tend to think that it could be the o2 sensor because if anything, my truck runs too rich, not lean.

 

It could be the 02 sensor. I have been told that the computer on our trucks can be finicky about which brand of sensor is used. A shop had originally replaced the 02 sensor when the light would come on at the same time each day. They used a generic 02 sensor. It still did it so they tried a different one, a Bosch made for my truck. It continued to come on so they got one from the Ford dealer and that pretty much stopped it. It still may come on once or twice a year but it does not seem to be for any reason, it doesn't come back, and it passes smog so I just let it go like that and not create problems for myself where none exist.

Many things can set those lights off. When my passenger side exhaust manifold cracked a couple of years ago, at first the motor pinged a lot (detonation) and then it stopped pinging after a while and the check engine light came on a lot. Also, at the same time, my ignition switch went bad and took out the line that went to to 02 sensor, among other things. It was weird that it all happened at once, but that's the way that it happened. Of course, it happened when I was 2,000 miles from home on my vacation. I got home, but had to drive for a couple of days with no heat and it was in dead of winter and very cold (the blower fan also lost power when the ignition switch went out).

What does that have to do with the check engine light? I am not sure, but the light came on a lot until I replaced the 02 sensor with the correct one, fixed the ignition switch, and replaced the cracked exhaust manifold. Actually, it stopped after replacing the ignition switch and the 02 sensor. But somehow, the cracking of the exhaust manifold started all of those problems. The sound of an exhaust leak and a whole bunch of pinging started at the exact same time. The pinging went away, I guess that the computer had to adjust in some way, but of course the exhaust leak remained since it was cracked (actually one of the studs broke off, by itself, while I was driving...). I know that it does not make sense but sometimes these things don't make any sense. The point that I am trying to make is to check for other problems that don't seem to be related to the light. They may be the cause of your problems.

 

Well, the major thing that bothers me is that i will not pass smog with that light on.

 

Take the bulb out.

 

Believe me, i have already thought of that. The only problem is the smog guys look at the dash when the key is first turned over and if they don't see test light come on, then you fail.

 

Yeah I hear you. I am trying to think of ways to fool them, since your truck is being such a PITA (I would usually advise that just fixing the problem is the easiest way). But the check engine light can sometimes be a real bugger, even though truck is running well, and cause headaches for the owner. I was thinking of swapping the lead from the ABS light to the check engine light, since they both come on when you start the truck and then go out. Since you are not being inspected for your ABS, putting the ABS lead to the check engine bulb would make it look like it (the engine light) is working properly. Of course the ABS light would not come on, but that's not part of the test and you can just switch it back afterwards. But I don't think that those bulbs have leads, they are wired on the circuit board. So then I thought about switching the actual words on the dash, the plastic - cut them out and switch the ABS one for the check engine. I really don't know if that is possible, I've certainly never taken my cluster apart to try that one! Or else, possibly there is a way to rig some other sort of bulb up in there behind the words "check engine" that comes on for a short period when started and then goes off.

I realize that this stuff sounds ridiculous. I've never had to do anything like this to my Bronco. But the emissions tests are discrimatory to people who own older vehicles. They are made to pass the same standards that a new vehicle has to pass. And quite often the people who drive older vehicles are the people who can least afford to pay big dollars to get an annoying light to go out on a vehicle that otherwise works fine for them, and gets them to work, and their kids to school, and does not emit any visible smoke. Not only that, the whole emissions testing thing is a big money maker for a lot of people and has not been shown to reduce pollution in any significant amount. The pollution is going to go down anyway, simply due to the fact that new cars are very environment-friendly, and the used cars that people drive are getting newer as a whole and they pass emissions more easily when they are old compared to some of the older vehicles now that have poorly designed and hastily added smog equipment.

So if you can get over on the system, I say go for it. If your vehicle was really THAT bad, it would be blowing smoke all over and not running well and would die soon anyway. You don't see many cars like that on the road these days. Twenty years ago, it was not uncommon to see cars blowing all sorts of smoke going down the road.