spark plugs cap and rotor are new
I failed my emmissions test my NO level was about 1800 and the limit is 900 I just changed oxygen sensor?
Take it to a mechanic. You will spend an inordinate amount of time and money trying to fix something that you cannot test., so you will never know if it's right until you fail or pass the next smog test.
I failed my emmissions test my NO level was about 1800 and the limit is 900 I just changed oxygen sensor?
Most likely your car has a three-way catalyst. These reduce NOx emissions as well as HC and CO. If this is the case, you may need a new catalyst.
High NO levels are caused by high combustion temperatures. Modern engines run hot to aid in the reduction of other emissions such as unburned HC and CO. The three-way catalyst allows this to work effectively by reducing the NO levels after the gasses leave the engine.
There could be other causes, such as an overly lean mixture or a bad sensor in the emissions control system or possibly a vacuum leak. A dealer or a good garage can hook it up to the diagnostic computer and tell you what the cause is pretty quickly.
If the HC and CO levels are well below normal, I'd look for a vacuum leak first. If they're in the normal range, the cat is the most likely culprit.
NOX can be affected by many things. It would be helpfull to know what the reading for CO and HC are and there limits.
If its running to lean it will cause combustion temps to go up.
NoX is from heat. Check your timing.
could be an egr valve problem
