Question about 2002 Mazda Tribute

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High nox on emmission but no engine codes

I went to emmissions and everything passed except NOx reading. It came in at 3.17 and Colorado only allows 2.0. I took it home and replaced the egr valve, air filter and changed the oil. I then added two bottles of the lucas Nox reducer and ran thru a tank of gas. then before I went to emmissions the second time I ran the car for about 30 miles to make sure catalytic converter was nice and hot. NOx cam it at 3.16. Still no check engine light and vehicle seems to run good. What can it be?

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Check for a vacuum leak by doing a smoke test and see where the smoke is pulled into the vacuum line.

Posted on May 26, 2017


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SOURCE: 1994 Mazda Protege 1.8 SOHC failed emissions HELP!

have your EGR system checked . sounds to me like its not working or clogged

Posted on May 03, 2009

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How to pass emissions test?

Are all the error codes ok? Sometimes a minor code will not cause a "check engine" light on the dash. If the ignition system is marginal it will continue. The results of the emmission test help diagnose. Usually Nox is too high. It's usually caused by a very high temp combustion temperature. Carbon buildup in the cylinder may cause. If the cooling system is marginal, it may contribute. Some advocate a decarbonizing effort. Double check all your connections, cleaning and scraping to bright metal may help. I found a disconnected ground wire. It seemed to make the difference between pass and not.

Mar 26, 2015 | Cars & Trucks

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High nox reading preventing emmissions pass

Your uncle could be right. It is always best to make sure you put the correct fuel for your make and model in the tank. Don't put in any additives unless approved by the vehicle manufacturer. The catalytic converter in the exhaust system is what reduces the CO and NOX in your exhaust. It has a catalyst in there which causes certain chemical reactions in the exhaust. Firstly the converter must reach operating temperature, so before you get the exhaust checked make sure your cars exhaust is nice and hot, a five minute drive up to the inspection station first thing in the morning may not get the converter to the operating temperature. The other problem may be as your uncle said. The injector cleaner may have put out certain chemicals into the exhaust that have put a fine layer of residue in the converter. This will block the NOX from getting to the catalyst and therefore stop or lower the reduction. You may have to replace the converter (they are expensive here in Australia) but you should try and take the car for a long easy drive in the hope that it will burn off the residue (if there is any in the converter) and then go and have the levels checked, the converter should be hot enough to do its job by then. You may also want to try another inspection station on the other side of town or another town depending on the distance, that will get the converter to operating temperature and the inspection stations meter may be calibrated better than the one you are going so it will give a better reading!

Apr 04, 2014 | 1999 Lincoln Town Car

1 Answer

What does emmissions no ppm mean

Google what ever your Emission Report has on it


ppm ---parts per million
NOX--Oxides of Nitrogen

Feb 17, 2013 | 1991 Chevrolet Cavalier

1 Answer

High Nox levels on emmission test

here are the possible causes of high nox levels, Misfire condition
Malfunctioning or improperly adjusted EGR valve
Failed oxygen sensor
Leak in exhaust tubing upstream of converter
Excessive carbon deposits in combustion chamber
Improper spark advance
Blocked coolant passage
Overly lean air-fuel mixture
Damaged cold air duct
Failed or malfunctioning catalytic converter
Corroded or damaged engine sensor electrical connections.the best advice is to take it to a emission specialist to check it out! good-luck!

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1 Answer

I got code 92 can you help...I did emmissions and it failed misserably on NOX.Any idea where i can find what this code means

NOX is usually something like an EGR Valve or engine overheating,at least in the inspection lane.
I don't have the code, but you can see if the Egr is working and pull it off to make sure the passages are clean.
Going to inspection on a cool day helps, and don't sit there idling,shut it off.

Aug 03, 2010 | 1998 Nissan 200SX

1 Answer

Failed smog

means that the hc,co2,nox, emissions are too high, you will need the numbers in ppm on the read out to begin diagnossis

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Can't get 95 cavalier to pass emissions with high nox already changed egr valve now what can i do?

The catalytic convertor could be the issue. A car in bad need of a tune-up won't usually pass smog, either. High emmissions is caused by either a bad cat or unburnt fuel. Start looking at the ignition system (spark plugs, plug wires) and give that thing a tune-up.

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Emmissions problem 1993 saturn sc1 dohc

the car is older that 1996 there for you dont need emissions testing. if you wish to pass, check the carbon canister and the egr valve. if the temp gauge says the cars not over heating and the engine doesnt appear to be hot, dont worry about it.

Feb 06, 2010 | 1993 Saturn SC1

1 Answer

Failed emissions....high nox

Sticking egr will raise everything except nox. Bad o2 bad cat hard to give an accurate diagnosis with out checking it

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