My car won't pass emissions test and shows no code for the computer when the engine light is on?

Question

what can I do to make it pass or at least find out what it needs so it will pass. I don't want to just start replacing and repairing everything. I live in Nevada.

the car is a 1992 Ford Mustang 4 cyl

also it was the co2 side that failed

Answer 1

You will only get a code if the problem is controlled by the computer. i.e. fuel pump..

So, your problem isn't a big one, but it's likely not "spark or fuel related"

Your emission control sensors must be working or again,you'd get a code.

I would start looking into what's coming out of the tail pipe. Start your car, put your hand over the tailpipe hole..only for a minute, it can get hot..and see if there is any black stuff on your hand, if so you have some problems. Put some fuel cleaner in/injection cleaner if it has injectors, then use some first grade fuel, run that through for a while, then see what happens.
I don't know what year your vehicle is, but if it's older, then it's just plain old wear and tear.. change filters, oil, gas, all that helps.

Go to www.http://batauto.com .. they are great and will help you for nothing.

Answer 2

Year, make and model of the car would be helpful.

What piece of the emissions failed?
CO, NOX, HC?

For those of us on line to help, you need to give us as much detail as possible.

CO2 is not a failure component, so if they said CO2, then I'd take the car else where to get it looked at. CO2 is a natural by-product of combustion.

If they said CO is the failure component, then it typically means not enough Oxygen being drawn into the combustion chamber. Check the Air Filter and O2 sensors. Air Filter would be the first thing to check.

Answer 3

My 01 Mustang did not get a pass in IL. today. It does have none factory modifications but has always passed with no problems. The tester said because of the upgrades, they (EPA) their computors are now catching the none factory modifications. My car is properly tuned and has cats with sensors. Now what their catching is NOT SUPPORTED which is this case is non original factory equipment. This will happen to any new veh. that has been tuned with non-factory tuner chips. My mechanic will research it and get back to me but until then we are all screwed. He has a new Challenger and he too would not pass with the tuner chip he installed.

Answer 4

Get a compression test on the engine. If there is low compression in cylinders 1&2, suspect a blown head gasket between the two cylinders. Repair will need a mechanical remedy.

Answer 5

Well if the car will not pass emmissions -
But throws no codes.

I would say take it to another testing facility.
Safe to assume that the equipment they are working with is not accurate.

Was the tech using a handheld scan tool - or diagnostic machine?

The handheld tools are not the best to use.

Answer 6

Hey I am here for the first time. I came across this question and I find the answers truly useful. I'm hoping to offer something back to the community and help others too.

Answer 7

,Like the other guy said we need year make and model is the engine light on and NO codes? How many miles is on the vehicle. General answer Tune it up, plugs ,wires ,distributor cap and rotor button. new air filter. You could have a bad catalytic converter.

Answer 8

try changing the oil, make sure the car is at operating temp when you get there, you can also try adding a bottle of rubbing alcohol or one of the other brands of emmision cleaner to your fuel tank, available at auto parts stores

Answer 9

Get a different mechanic, and get a tune up.

Answer 10

lack of info hinders help....why doesnt it pass? what year? what engine? ever been tuned..... people are shocked when i say you need to tune your car every 100,000 miles....lol