Here in California, biennial smog or emissions testing is required in order to renew registration. Biennial means that you need to have this testing done every two years. The reason behind smog testing is to ensure that every registered vehicle meets certain basic requirements when it comes to vehicle emissions. This is in an effort to protect our environment and reduce the volume of greenhouse gases that we release into our atmosphere.
Failing an emissions test can definitely be a shock, especially if you thought your vehicle was running fine. There are certain reasons why your vehicle may have failed emissions, and all will more than likely require a repair to fix. Let's look at some of the most common reasons why vehicles failed emissions testing:
- Your check engine light is on - no car will pass emissions with a check engine light on. Depending on the reason for why the check engine light is on in the first place, you'll need to have the underlying issue fixed and then have the OBD system reset.
- Bad catalytic converter - the catalytic converter is essential to converting harmful gases into less harmful gases before they are released from your vehicle. If the catalytic converter is faulty, you won't pass emissions testing and will need to replace it.
- Faulty oxygen sensor - an oxygen sensor that isn't working properly can cause the wrong air/fuel mixture to be injected into your engine, which will also prevent your car from passing emissions.
- Dirty air filter - a dirty air filter can cause problems with filtering carbon monoxide, which can fail an emissions test.
- Worn spark plugs - worn spark plugs can decrease your vehicle's fuel efficiency and cause start-up issues.
- Evidence of tampering - if there is evidence of tampering with the emissions system, this is an automatic smog test fail.
These are just some of the most common reasons for a vehicle to fail emissions testing. If you do fail an emissions test, we invite you into one of our convenient Family Auto Service locations for an inspection and diagnostics. We can determine why you failed emissions and provide you with the repairs necessary to help you pass on your next testing.