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I need a smoke test!

So your “Check Engine” or “Service Engine Soon” light is on? What to do?

I recently fielded a call from a car owner asking “how much was a smoke test?” Hmm, I thought “why?” So, I asked him why he felt he needed a “smoke test.” He responded explaining his check engine light was on, and he brought it to the parts store, they scanned it and told him that he needed a smoke test! Further, he would need either a charcoal canister or a vent valve.

Hmm, we hear this sort of thing a lot. ‘Diagnosis by trouble code,’ I call it. Great way to sell parts, but the wrong way to repair cars! Often I get these inquiries after the person has replaced the charcoal canister and vent valve and the light returned again after a few days.
So let’s clear this up!

The check engine light illuminates when you have a problem that affects your vehicles emissions system. There are dozens of trouble codes that will cause the check engine light to come on! Many more will not. They will be stored in the computer memory of one or more of the modules that control your vehicle, yet some will not even turn the light on because they are unrelated to emissions.
Many ‘part store scan tools’ record only the most recent codes and, little if any other important information.

Simply a trouble code is not a diagnosis of a problem. Better, to think of it as a “road sign” pointing you in a direction toward your destination.

In this person’s case, he had a code that indicated a problem with the evaporative emissions system. Which in some cases requires replacing a ‘charcoal canister or vent valve’ but, it could also be many other things as well.

A ‘smoke test’ is a quasi-technical term for testing the evaporative system for a leak (allowing fuel fumes to escape into the outside air.)
However, one doesn’t jump into a ‘smoke test’ which takes time and can lead you down a “rabbit hole” without first performing some preliminary tests that rule out other causes that might initially seem to require a “’smoke test.’ Very often the problem is actually component related or a wiring problem.Often a ‘smoke test’ will reveal nothing when testing the charcoal canister because the smoke is absorbed by the charcoal giving a false negative result.

As I stated earlier, we see many people come to us after they have spent hundreds of dollars chasing a problem by installing parts that were in question because of a trouble code that led in that direction. Admittedly, some get lucky and land on the right part early on. Most spend money needlessly only to find out it was something much simpler than they thought, like a lose connection, cracked hose or other minor item needing replacement.

We would recommend leak testing the evap system based on some preliminary tests and evaluations that include scanning for codes but we also look at many other factors together, which help us evaluate and determine your problem quickly and accurately, usually in an hour or less.
Our equipment and knowledge is what makes the difference. Then if you need a ‘smoke test’ we move to that.

To sum it all up, we applaud those ‘do-it-yourselfers’ trying to save themselves some money. When it comes to a ‘check engine light’ you really are better off bringing it to the professionals.

We perform free scans and we are ASE certified technicians with many years of experience repairing just these sorts of problems.
Save your money have it professionally diagnosed and get the problem fixed right the first time every time, guaranteed!
We offer a FREE basic scan for trouble codes! So what do you have to lose, but a few minutes of your time to stop by and have it checked?
Give us a call or stop in! We are here to help!

Thanks again for listening!

We look forward to serving you in the future!