alrighty...i have a 94 accord lx 5 speed...just installed a whole new exhaust system..header,down pipe,"high flow cat" and cat back exhaust...when i went to take the O2 sensor out of the old header it was a pain...so we sprayed blaster lubricant on to help break it..finally got it off...put on the new aftermarket header and since i put it on the check engline light has been on...tried to reset it by dissconnecting the battery but that didnt work..came right back on...could the spray mess up the sensor or could it be the entire aftermarket exhaust or the fact i no longer have a OEM cat...please let me know if you can help....thanx...

 

Since the O2 sensor came from the header, the new cat would not affect it at all. The spray might have done something to it, before you replace it, try cleaning it by holding the sensor tip in a torch flame for a few seconds to burn of any residues and build up.