hey guys wondered if any of u could help i was driving home from work this evening when the engine light came on as today i have attempted to fit a stainless header i have had the sensor unplugged what may the problem be is it possible for it 2 have just popped out of the plug and would this cause the engine light to come on

 

have actually heard of a spark plug coming all the way out, but not an oxygen sensor. i guess that is the sensor you are referring to.
the new header had allowance for the oxygen sensor, right??
there is a code that references the oxygen sensor - so yes, the light would come on for a defective oxy sensor.
need to read the code - could be something else.
also, i would check the wiring right where it comes off the sensor.

 

i think the sensor has come out of the plug in clip not the manifold, i neva got the new manifold fitted anyway as its 2.5 inch diameter and will not fit into the standard cat so hav gotta wait to order decat now, unless anyone knows how i can get it to fit the standard one

 

if the car was running with the sensor unplugged, it'll bring on the light
also, don't use penetrating spray (wd40 and suchlike) near the sensor - contains caustic which'll render the sensor useless

 

sensor is coming on when engine is hot the plugs werent unclipped at all so can only put it down to penetrating spray that has contaminated the sensor so new one on order now

 

well, i had that too; and replaced a sensor that only had i would say 12 to 18 thousand on it. did not do any good.
it seems like (at least in my case), that it would need some time before the conditions would get to the point that the cel (for oxy sensor) would come on. yes, it would have to be in warmed - up state - varied somewhat as to when it would come on.

the sensor in my case (i hope since i am not finished with the rebuild) was (i hope) coming on because of what it detected in the exhaust - and that is that i had 2 bad valves and i don;t know how many bad valve stem oil seals. obviously the sensor cannot read itself; so it may be reading correctly, and the code that is causing it to come on is caused by that which the sensor is reading.
there are methods to check the oxygen sensor; i would like investigate that at some date - but if it requires a scope then it is out of my league. may be able to be done by just a vom meter - different for different makes and models.