Please provide detail info if possible.
Most vehicles fail emissions tests, not because of anything related to tune up or oil change, but rather major emissions systems failures such as; catalytic converter, etc.
A tune up and oil change may help, but it will not alone solve your emissions test issue.
Get the car check by a reputable mechanic before trying the emissions test again.
By the way–more info on your vehicle; mileage, make model, condition would help to better answer your question
an oil change won’t help. A tuneup may help a bit. You probably got some test results with output that will help a mechanic determine what is wrong. If a costly repair is out of the question, there’s a fuel additive that you can buy that will help you pass any emissions test with flying colors. I had a car a while back that would have required replacing the engine to fix. I used the fuel additive and it worked like a charm. It was called “pass any emissions test” or something like that. In any case, you may just have a bad oxygen sensor or air filter, either of which won’t cost much.
Unless you’re burning oil, an oil change won’t do a thing for you. You need to see if you do need a tuneup first. Other things to check for is loose , disconnected, or broken vacuum lines, or mis-routed. THOSE can really ***** up your emissions! Also the little tiny hard plastic lines to your A/C controls, if they’re broken, you’ll lose vacuum, and maybe it won’t operate your emissions equipment as well. So you need to hunt for any hoses, hard or soft, under the hood that need replacing. Check the EGR valve, it can dump exhaust gases into the intake, if it’s stuck, or the vacuum line to it isn’t working.
One other trick is to use Methanol alcohol, in gas treatment bottles, to trick the Emissions sensors, as it adds Oxygen to your system. It will help, but if you have a high-mileage car, and it’s WAY over the limit, it may still not pass. I’d put 2 to 3 bottles to a 1/4 tank of gas, to enrich it. I’ve done that before with my old cars, and it helps.
Also, you need to go into the station with the car HOT, this gets your catalytic converter up to temp, if you bring it in cold, it won’t work properly, and mechanics/inspectors don’t tell you this. So go run the car on the Interstate for 10-15 minutes before hitting the station, and hope you don’t have to sit too long. There’s nothing wrong or illegal about this, it’s just that the car needs to be warmed up, and most stations won’t tell you that.
- The Gremlin Guy -
I just experience a similar thing here in Davidson County Tennessee. I have a ’93 Suzuki Sidekick which failed on HC and CO on a OBD1 on 7-28-07
Limits: Test 1
HC 220 343
CO 1.2 7.51
The vehicle had 127,000 miles and had been driven about 1,000 drive in the last year. Last TU was about 1 year. OC was 6 mos.
I did a full TU (plugs, wires, air filter& fuel filter) and OC. I put 12 oz of Guaranteed to Pass fuel additive into 5 ga of unleaded then topped it off with 5 gallons premium unleaded. I drove 80 miles highway. Added 5 more gallons of PU, drove 20 miles highway and tested 24 hours after the original test. Results: Passed
Limits Test 1 Test 2
HC 220 336 152
CO 1.2 7.56 .47
I hope this helps.
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