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Engine & Transmission Tips • Issue 5

The Check Engine Light

February 12, 2021

Keep Your Check Engine Light In Check!

uth check engine light imageUgh, my Check Engine Light came on again. Kinda worried, I brought my car to the garage. They did a “check” and, for $115, told me it was my gas cap, which they replaced for me. My gas cap? Really? Somehow connected to the Check Engine Light?

Amazingly, that whole stressful experience, and $100, could have been averted if I knew then what I’m about to tell you.

The dreaded Check Engine Light (CEL) is just that, a light. It comes on telling you something is amiss. What it doesn’t tell you is the fact that you can check the problem yourself, saving tons of money over taking your car in for service.

First let’s talk about the most common vehicle issues that trigger the dreaded Check Engine Light illumination. Since you likely have an indicator light on your dash board for low oil, low coolant, low tire pressure, brake issues/ABS, airbag warnings, and your battery. So, the Check Engine light is actually reserved for more sever issues.

UTH car dashboard warning lights

According to CarMD’s Top-10 issues recorded from Check Engine diagnostics were, here’s what you may be looking at behind that orange glow:

  1. Replace ignition coil(s) and spark plug(s) ($391.42)
  2. Replace oxygen sensor(s) ($244.04)
  3. Replace catalytic converter(s) with a new OEM catalytic converter(s) ($1,371.17)
  4. Inspect for loose gas cap and tighten or replace as necessary ($25.86)
  5. Replace ignition coil(s) ($217.91)
  6. Replace evaporative emissions purge control valve ($149.52)
  7. Replace mass airflow sensor ($340.58)
  8. Replace evaporative emissions purge solenoid ($153.70)
  9. Replace fuel injector(s) ($449.73)
  10. Replace thermostat ($244.61)
Crap! No real good news there…

But, the CEL is a warning indicator that a persistent problem exists. It may be giving you time to rectify a situation before it becomes critical. Luckily, when that light comes on, your car’s computer stores the “error” code in memory, to be read later by a variety of user-based diagnostic tools.  Even more awesome, these tools are also available to consumers, and are called ODB (On-Board Diagnostics) readers or scanners. These scanners “plug-in” to a port called the DLC (Diagnostic Link Connector) located under the dashboard, usually close to the steering wheel.

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NOTE: On some vehicles the connector is behind a removable panel piece. Check your manual or the megalithic Google.

ODB-II is the current standard, as of 1996. And accordingly all OBD scanners available for purchase should be OBD-II compliant. These devices range from impossibly cheap to stupidly-expensive, and their features follow that gamut.

The cheap ($9) ones display the numeric code only. Going up the chain, the next level displays the written definition of the error code. The next level have graphical displays, which add greater insight to the information your car is relaying to you. And then there’s a departure in the type of technology implemented in OBD Scanners, namely wired (aka handheld) or wireless. As the name implies, the handheld scanner plugs into the port via a wire, and has its own screen with the advantage of no-fuss, quick results. The wireless models also plug into the port, but you access them with your smart phone or tablet, with the advantage of access to more data and solutions.

uth obd scanners

According to, the best ODB2 scanner on the market, which is a handheld, runs about $100 and includes a plethora of features like a large screen, lots of data access, and even repair explanations.

Interestingly, if you’ve gotten one of the major insurance company’s “safe-driver” monitoring devices, you most likely plugged it into your DLC port. (And, it is certainly telling your insurance company more about you than just your driving habits, like your travel, dedication to scheduled maintenance, and much more. And, they’re selling that info to other companies as well.

To summarize, just about everything that happens inside your vehicle is tracked by it’s on-board computers. (Yes, there are probably more than one.) From a faulty gas cap, (really!), to low tire pressure, to impending engine part end-of-life, or even a failing catalytic converter, the information is just waiting for you to access it, and learn more about your car.


Fraser Engine Co. specializes in remanufactured engines. Any diagnostic computers in your car will operate exactly the same with our products.Visit our home page to find the right engine, if yours is ready to retire. They’re less expensive than you think, and come with new parts and full warranties!


If you’re thinking about upgrading your car, Call Fraser for a world-class remanufactured engine or transmission.

Thinking about building a replica with an american-made engine? Fraser has the right engine ready for you!