I have a 1999 f150 with the 5.4 v8. I took it into the shop because the service engine soon light was on. It said that the o2 sensor was bad and the mechanic replaced them. The next day the service engine soon light was on again, so I took it down and it was the same thing. They replaced them again, thinking the other ones were faulty. The next day it happened again so they replaced them again. And now the light is on again and they say it is the o2 sensor again

 

what codes came up? once you replace them .. they shouldnt be faulting out.. did you tech clear your check engine light and clear your codes... after replacing o2 sensors?

 

What codes are you getting exactly?

There are no codes that specifically mean "bad O2 sensors."

 

im not sure what codes exactly but the mechanic showed me when he plugged it in and it said O2 sensor. they cleared it after each time and today they cleared it but i came back on. i only paid for the first O2 sensor, he paid for the rest, so i know he is not trying to screw me over. they also just replaced the computer and some coils.

 

Without knowing exactly what codes or concerns you're trying to fix, you're shooting in the dark.

How is the truck running? Runs okay? Stalls? Runs rough?

 

the codes come through but it converts them to the actual problem i think. it is running pretty good but before they changed the o2 sensor the last time it was running a little rough

 

We need the exact code number before we can tell you where to start.

And O2 sensors have no effect on idle quality and will not cause a running problem. Period.

 

aright well I’m gunna take it down on Monday so i will get the code then. also I’m not sure why it was running rough but it seemed to get better after they fixed the o2 sensor, at least for a little bit.

 

Instead of taking it to the "mechnanic", take it to AutoZone and have them write down the code(s). Then come back here and do some research using the SEARCH feature.

I'd hazard a guess that you're getting the all-too-common "lean" codes (P0171 and/or P0174) which, of course, are NEVER caused by O2 sensors but usually by a vacuum leak.

I'd also see about getting some money back from that shop since they don't seem to know how to diagnose fault codes.

Steve

 

they arent bad if they arent showing a code... only time they are bad they show a code.... not sure what kind of mechanic your going to but your getting the run around.... dont be replacing them if they arent bad.. but then again its your money...

 

[QUOTE
I'd also see about getting some money back from that shop since they don't seem to know how to diagnose fault codes.

Steve[/QUOTE]


i couldnt agree more with steve.. im not the best in the world when it comes to working on vehicles.. but i know when im getting screwed around...

 

i got the code. it is P0141. then it says 02 sensor heater, sensor malfunction, bank 1 sensor 2.
also i'm pretty sure im not getting the run around because i only paid for the first things they did. the last 3 o2 sensors were free.

 

I looked it up and what i found said that i should check the wires. i took it down to the shop and they found 2 wires that were messed up. they fixed the wires and the light went out, unfortunately that only lasted a day and the light is on again. please help me! i cant think of anything else to do to fix it.

 

as the other guys have said you should check for a vacuum leak. It could also be a failing COP in there somewhere. Did you drive through water recently?

 

I did have a vacuum leak in the beginning but they fixed that.