how can you tell if your o2 sensor is bad

when was the last tune up done?

I gave it a tune up a week ago plugs, cap, rotor, and the plug wire are about 5 months old

air filter? and is the firing order correct?

Thanks for trying Jonathan but if you can tell me without asking a question it would be more helpful

He's probably trying to narrow down what the problem is with your car, bigheeman. Your oxygen sensor is part of the emissions control system, so when the 'Check Engine" light comes on, it MIGHT be the oxygen sensor. There are many components in the emissions system, so when this light comes on the only way to tell which component is bad is to have it analyzed with a scanner that plugs in and runs a diagnostic check. This is done by a mechanic and ranges in price. If the 'Check Engine" light isn't on and you are just guessing at what the problem may be, then it would probably be good to take it to a reasonably priced mechanic and have them help you get it going. There is no way around taking the car to a mechanic, if you aren't able to diagnose the problem correctly yourself.

oh so the check engine light has to come on first? Well my check engine light doesnt come on i was just trying to figure out what i can check. thanks for the advice

it doesnt mean your oxygen sensor is bad, it means something else is wrong and the oxygen sensor is adjusting to compensate for it...but since you don't feel like answering questions to help narrow it down, you should just go to a mechanic.

Sorry Jonathan I didnt really mean i didnt want to answer questions its just that its already been a few days and I really needed a answer immediately. Your right about taking it to the mechanic. So again sorry about the misunderstanding and keep giving advice to those like me that look for them

sounds like a pcv valve clogged up or valve seals could cause it to smoke. replace the pcv valve and go from there.

I have a Honda accord EX 99 how do I know when the oxygen sensor is bad

I guess I don't get an answer have a bless day

i have a 1997 honda accord SE timing belt broke and broke the crank sensor. i replaced the crank sensor re timed everything ,new plugs new wires but it still wont start.

Sounds as if it is either off time or possibly when the belt broke it did damage to the valves is that engine an interference engine? If so it is most likely when the timing belt broke it allowed a piston to hit a valve or multiples and there is most likely either a hole in a piston or bent valve[s]

Is there any problems with backfiring? Backfiring can be a good symptom for either problem if so I would recommend do a leak down test on the head and seeing if you have valve damage if no valve damage the issue could be numerous things from electrical to problems with the bottom end of the engine.. [pistons]