Skip to content

Mechanically Speaking: Married to the check engine light

"The main reason to react is to save yourself some money in the long run"
Mechanically Speaking image.indd
Mechanically Speaking

Sometimes I feel as if my customers think I own their check engine light. What do I mean by this?

I have talked about this orange engine symbol light before and most vehicle owners have had this light come on inadvertently while driving. Because it is an orange warning light and not a red warning light it does not require an immediate response.

This light is present (government emission standard mandated) in order to inform the driver that their vehicle is polluting the atmosphere at a rate of 1.5 times the amount it was designed to. When this light is flashing while you are driving your vehicle’s catalytic converter is possibly becoming damaged and left long enough will no longer function adequately and therefore will need replacement. (These are expensive puppies and you may have more than one). Do not drive with a flashing check engine light!

Many drivers, on seeing this light come on, will simply try to ignore it. Many times there is not a noticeable change in the way the vehicle drives, so why over react? As I have written about before, the main reason to react is to save yourself some money in the long run. When that light is not on your vehicle is likely running inefficiently and also experiencing a significant increase in wear and tear.

Upon booking an appointment with your mechanic and/or googling the crap out of it in order to offer some advice to your mechanic, you now place control of that light into your service providers hands saying “The light is on. I want it off. How much? I think it is the oxygen sensor or something.”

Well, at this level a crystal ball is the only way to offer a solution. The onboard diagnostic systems of modern day vehicles are very robust. They do a very thorough job of keeping that light off. Therefore in most cases when the light is coming on it is for a good reason. Testing is the only proper way to find a solution and that takes time and money.

Let it be decreed that there are way more than a 100 reasons that that light could be on. Probably more than 200 reasons. Given some time, some tools and some knowledge your mechanic should be able to narrow down and then pinpoint the reason that that recalcitrant light is currently coming on. The operative word is “currently”. Yes, the repair procedure that turns that light off today may not be the same procedure that turns it off next week, or next month or next year. It very likely is not on for the same reason.

In the customer’s mind though the symptom is exactly the same. “The light comes on while I am driving. You replaced the sensor and now it is bad again. That part is guaranteed? Is it not?” I and many other mechanics now feel married to that light.

There are many ways that your mechanic will deal with this new marriage. There are many who will simply ask for a divorce. “Those cars all do that. Don’t worry about it.” Then there are those that will manipulate  the marriage simply placating the spouse. “When the light comes on again just come by and I will turn it out.” Then there are those willing to work on the marriage. Time will be spent discussing the situation at hand. “Last time the light came on this was the reason. This time the reason is different. There are four oxygen sensors on your vehicle. One was bad last month. Now a second is bad. Maybe we should be proactive and replace the other two.”

Working on a marriage can be a hard row to hoe.

Trail’s Ron Nutini is a licensed automotive technician and graduate of mechanical engineering from UBC. E-mail: nutechauto@telus.net