99 Honda Accord-Check engine light and getting smogged?
I have a 99 Honda Accord. My check engine light came on recently and my coworker hooked up the code reader (or whatever its called) and got code P0420 which is "catalyst system efficiency below threshold". I read that it could be an oxygen sensor OR catalytic converter. My coworker cleared the code and I purchased the sensor. He cleared the code Friday, and it hasn't come back on as of yet. I have to get my car smogged for the registration. My coworker said I should do it now while the light is off. He said if the check engine light was going to come back on, it would have come on very soon after it being cleared. Does anyone know if this is true? I don't want to take it and have it fail, and I have the sensor so I could have a coworker replace it before I get it smogged. I live in California, I think that our emission standards are Really high here. Should I attempt to get it smogged while the light is not on?
Get it on the highway and drive it for a couple hundred miles. If it doesn't come on, you should be good.
Yes it is true the P0420 code means the cat is either worn out or the oxygen sensor behind it is faulty, and you were right for trying to replace the sensor first. However, clearing the code doesn't mean the car is ready for inspection while the engine light is off. There are parameters called inspection readiness (I/R) monitors that need to re-calibrate. This can take several days of normal driving to complete, and depending on the laws, if you have too many I/M monitors that are "incomplete," the car will be rejected during the testing process and you will have to drive around longer until they finally set. If your co-worker has an up-scale enough scan tool, it should be able to populate a list of these monitors and whether or not they are set.
The oxygen sensor is not the problem, don't replace it, and driving the car a couple hundred miles is a complete waste of time and money. You don't need to go nearly that far. California allows one monitor to be incomplete when you go through the smog test. Your co-worker friend is on the right track whether he knows it or not. You need to drive the car long enough for all the monitors to run but not long enough for the computer to see a problem with the cat, it is the problem for sure. Drive the car and have him check it each day, as soon as the monitors are complete, get it smogged and you'll pass.
If you drive the car a long time the p0420 will set again. There are 3 ways to fix your problem if you really want to. The most expensive and dumbest is to replace the cat. The engine is worn and it's oil burning will ruin your new cat rapidly. You could take the cat out and clean it by filling it with solvent and soaking it over night and re-installing it which would last quite a while because the Honda cat is way better than anything you'll be able to buy. The last way is to cheat and buy a small mini-cat adapter to trick the computer into thinking the cat is good and these actually work well but they are not legal.
http://www.bigdaddiesgarage.com/mini-cat-cel-fix.html
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