The Dreaded Check Engine Light

By Mister Transmission

Some of us are old enough to remember the pre-1981 vehicles, which weren’t equipped with on-board diagnostic systems. Much has changed and now we can learn about problems before they ruin our ride!

Cars born before 1981 would indicate a malfunction usually through one of four “idiot” lights, which would tell us that our car had lost oil pressure, over-heated, stopped charging the battery, or lost brake pressure. The problem with these lights is that they usually came on after the damage was already done due to their simplistic sensor systems.

Also, these sensors and systems didn’t give a hoot what was coming out of our tailpipes as far as pollution was concerned. That changed in 1981 when new regulations came out requiring catalytic converters for all domestic passenger vehicles.

The Advent of On-Board-Diagnostics

It was taken a step further in 1996 when automakers were required to upgrade their vehicles to a sophisticated system consisting of central processing units (CPU), sensors, actuators and valves known as OBD II (On-Board Diagnostics). When a problem with the vehicle’s engine, transmission, emission system or any of the myriad of sensors monitoring the aforementioned systems occurs, a code is stored in the computer and the “engine light” is illuminated to alert the driver.

As you may know, almost everyone (including the manufacturers who should know better) refers to the light as “the engine light”. This is one of those situations where one of the first manufacturers to equip their vehicles with on-board diagnostic (OBD II) systems called it an engine light, and now it’s the generic name for lights of that nature.

A few manufacturers did refer to it more accurately by calling it the Malfunction Indicator Light (MIL), since it true purpose is to indicate a malfunction in the systems the computer monitors, but not many.

The problem causing the light to come on could very well be a transmission fault. A technician would perform a scan to retrieve the trouble code from the computer and then cross-reference it to determine what area is at fault.

Where most technicians make an error, is to find a transmission-related trouble code in the computer, and then assume that it merely needs a flush, service, or “magic potion” poured into it to correct the problem. Fluids or aftermarket additives cannot fix worn clutch plates, broken gears or defective solenoids… only replacing them can.

When your vehicle has a transmission-related fault code in the computer, let us remove the pan for a visual inspection. If there is excessive metal on the magnet and/or the fluid is burnt, the transmission is going to need to come out.

If your engine light is on, please contact your local Mister Transmission and book an appointment for our FREE 21-Point Multi-Check Inspection which includes removing the pan on your transmission.

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Customer Reviews
They did a great job...
Warren Pulling
They did a great job with my caravan. Great service, quick turn around. Thanks
Date: March 9, 2026
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Got all my fluids changed...
Ahmer Zaki
Got all my fluids changed here on my Mercedes very good prices and they do an excellent job definitely coming back here and would highly recommend
Date: March 7, 2026
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This location is the best....
Brandon Callaway
This location is the best. Chris is amazing to deal with. Had a torque converter and rear diff replaced and they did it really fast. Highly recommend these guys. 5 out of 5 stars
Date: March 7, 2026
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Dan was the best. Will...
Deanna
Dan was the best. Will always come back!!
Date: March 6, 2026
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They did a great job...
Doug
They did a great job in keeping us informed of the process andfinished all the work in a timely and professional manner. Would recommend this shop to anyone needing transmission work for an honest and thorough job. I have used them exclusively for all my transmission needs for the last 15 years. 5 out of 5 stars definitely
Date: March 6, 2026
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I recently brought my car...
Chris Elliston
I recently brought my car to Mr. Transmission to have a wheel bearing and axle shaft replaced, and I couldn’t be happier with the service. The price was very fair, and the work was done professionally and efficiently.What really stood out was the customer service — they even drove me home while my car was being worked on, which made the whole experience much more convenient. It’s not easy to find a mechanic you can truly trust, but these guys are honest, reliable, and clearly care about their customers.I would highly recommend bringing your vehicle here if you’re looking for a trustworthy and dependable mechanic shop.
Date: March 6, 2026
Website: Google
Towed our Rav4 from the...
H M
Towed our Rav4 from the dealer who said we needed a new transmission to Mr.Transmission Exeter RD. London. Thinking we had to get a rebuild, Sanjay and his tech found it only needed a new axle and rear coupler so $000's less and so happy to have an honest shop who did not take advantage.
Date: March 6, 2026
Website: Google
Thank you, Giorgio! An honest...
Bobh Yyz
Thank you, Giorgio! An honest operator…I stopped by his Mister Transmission as a mechanic diagnosed a slow leak under my car as transmission fluid.Regardless of being tied up, Giorgio came out front to my Jeep Wrangler, crawled under, came back up, and said looks and smells like oil.He suggested the auto service shop next unit over. We went in and our explained the situation to the operator. I’m in good hands with the service shop now.Bottom line: Giorgio’s good turn, at no cost to me, quickly helped steered me in the right direction.
Date: March 6, 2026
Website: Google
Was there earlier today and...
Breanne Ferguson
Was there earlier today and I must say one of THE BEST SERVICES I've had in a long time. A good mechanic or even someone good with PROPER diagnosis even if there isnt anything wromg are very hard to come by now a days and I feel very confident that my vehicle was is great hands today. Those working there truly care about helping their customers and easing minds that are over thinking about their vehicle. I highly recommend seeing Sanjay and his Mechanic in the back! They were awesome!Again BiG BIG thank you to Mister Transmission today!Well definatley be back again if any other issues pop up (hopefully not in the foreseeable future)!
Date: March 6, 2026
Website: Google
Great, fast and easy
Holden DeGroot
Great, fast and easy
Date: March 6, 2026
Website: Google
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