How to Pass Smog Test With Sensor Problem

If you have an old car, especially old Corolla, you might fail to pass SMOG check due to Mass Air Flow Sensor failure. It could cost you $500 to fix it, however, you could do it yourself to clean this up and pass the SMOG check under $10. Here is what I did.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• OBD reader
• Carb cleaner

1. If your car's Check Engine light is on during SMOG check due to mass air flow sensor problem, which is common among old Corolla cars, don't take the auto shop's recommendation to spend $100 for a diagnostic test first and then fix the problem in order to pass the SMOG check.

2. Go to Autozone to get a OBDII Reader, which should be free, to clean up the error code, or better, bring your OBD Reader to the SMOG Check station and do it on the spot.

3. If you cannot get a free OBD Reader, no worries, all you need to do is to clean the Sensor. In order to do that, go to Walmat to get a bottle of Carb Cleaner ($4 or so), open the trunk, remove the Sensor, spray the Carb Cleaner to it and clean it up with a cotton stick. When it's dry, put it back.

4. Now clean error code without an OBD Reader. Disconnect battery for a few minutes, then connect it back on. Start the car, you should see the Check Engine light off now.
   
   It's not over yet, with the power off, the car loses all of its measurements, before you heading to the SMOG Check station, you should drive 100 miles or so, in this way, the car's system will pick up all the measurements. If after driving 100 miles the light is still not on, you are good to go!