Matching You with a Pre-Screened Smog Check Center You will Love
Free Online Smog Check Diagnosis
$500 Free Consumer Repair Assistance
Failed Emissions Test
How to Pass the Test
Who Else Wants To Pass the Smog Check
Miles: 
Which Type Should I Choose?
 
   
    Forum > Failed Smog Test > Question

Join the community and post your questions. Ask-A-Tech right now!
 
 



Failed Smog Test
 

1997 Jeep Wrangler Failed Smog Check for High CO and HC.

My 1997 Jeep Wrangler failed emissions for high Hydrocarbons, and high Carbon Monoxide. I have installed a new Catalytic Converter and Oxygen Sensors as well as the Gas Cap (all of these PASSED on the inspection. Could the failure to pass emissions be attributed to the quality of gas I'm using? This Jeep has been parked for prolonged periods of time and perhaps needs a good hard running and better gasoline grade (91 octane for example). Any suggestions very much appreciated.


Answer:  

The gasoline grade will not help pass your Jeep Wrangler pass the smog test, but fresh fuel might depending on exactly how old the fuel during the smog test was. If older than 2 months we recommend re-testing with fresh fuel.

With that said if fresh fuel does not get your Jeep to pass and since you mention having already replaced the catalytic converter and oxygen sensors (and we'll assume the job was done properly) we have to recommend going back to square one with a hands-on diagnosis.

The combination of high CO and high HC usually indicates a air/fuel control problem. Depending on how high CO is in comparison to HC we can determine whether the fault may be with the ignition system or fuel control system. Higher CO than HC emissions usually indicates a rich fuel mixture and would suggest inspecting all emission sensors which control fuel, such as the oxygen sensor(s), engine coolant temperature sensor, and mass air flow sensor.

Read more about smog check failures here.


posted by SmogTips Support
 


Related questions and answers you might find useful:

by Sales

by Sales

How Do I Get a Smog Check Waiver? by Margaret

Do I Need a Smog Check This Year? by Joy

Mini Cooper DMV Registration Due in 5 Day Won't Pass Smog by anne