How to Use the Dreaded "Check Engine Light" as a Selling Tool

Check engine light as a selling tool.jpg

Vehicle owners often assume the check engine light is unimportant and ignore it.

Educating customers can make you money. Plus, it can help protect them from additional repairs.

On the Internet, customers read that the check engine light (CEL) is merely a nuisance triggered by a loose gas cap. Such delusion causes them to visit your shop for another service (a lowly oil change, perhaps) without mentioning the engine light. With all the misinformation floating around, it’s up to you to inform and educate vehicle owners about their CEL. 

How to demystify the check engine light and increase sales   

The check engine light –  otherwise known as the service engine soon light –  is a handy tool for increasing sales. Addressing CEL-related issues also protects your customer and provides them with peace of mind. 

So, next time you have a car in for an oil change, and the dashboard is lit up like a Christmas tree, don’t ignore the problem. Use the following strategies to educate vehicle owners and make money at the same time. 

Answer the question – what does the check engine light mean?

Typically, customers know nothing about the check engine light. Does it mean the vehicle needs an oil change? Did the gas cap not get tightened down last time they stopped at the Texaco? 

As a professional, you understand the CEL can indicate serious problems. It can be triggered by anything from low battery voltage to worn internal engine components. Take the time to explain what the service engine soon light really means to the vehicle owner.

1. Start by telling them about onboard diagnostics:

Vehicles built after 1996 are equipped with onboard diagnostics. At the heart of this system is a computer, called the engine control module (ECM). The ECM monitors vital powertrain and emissions-related functions. When it detects a problem, it illuminates the CEL. At the same time, it stores a diagnostic trouble code (DTC) in memory. 

2. Next, explain the ramifications of the check engine light:

There are countless reasons the ECM may turn on the CEL. While, yes, it may be due to a loose gas cap, like YouTube says, it may also be caused by something more serious, like an internal engine problem. Not addressing the service engine soon light can lead to further damage and an inflated repair bill. 

3. Offer a free check engine light code scan

Pulling DTCs from the vehicle takes under five minutes. So, why not offer this as a free service to your customer? 

Even if the CEL isn’t on, you can hook up to a vehicle when it’s in for maintenance or repair. Check for any pending codes and look to see if all the OBD monitors have run. If they haven’t, there may be a problem that’s holding them back (or the customer may just have cleared codes or disconnected that battery). If you find pending codes or incomplete monitors, inform the customer there may be a problem.  

4. Accurately describe diagnostic trouble codes and potential causes

If you find DTCs stored, explain to the customer what they might mean. A quick Google search will give you some ideas ( is a good site). Or, you can hop on a repair database like ALLDATA or Identifix. Be sure to tell the customer the code is NOT a diagnosis. It’s only an indication of where to start.

Take, for example, code P0131 Oxygen Sensor (O2) Circuit Low Voltage. Just because the O2 sensor is in the DTC title, doesn’t mean it’s the problem. The O2 sensor measures the amount of oxygen in the exhaust stream. When it outputs a low voltage, that means there is a lot of oxygen in the exhaust and the engine may be running lean. So, not only could the DTC indicate a bad sensor, but also an engine performance issue. It could also be set due to a circuit fault, an exhaust leak – or even a problem with the PCM. 

Explain to the customer the general direction the code is telling you to go in. Then, let them know it will take a thorough diagnosis – and plenty of time – to pinpoint the problem. Also, if the DTC is severe, you may want to expand on that. For example, if the code is for a misfire, let them know they could be damaging their catalytic converter by continuing to drive the vehicle. 

5. Don’t give away diagnostics

After the code scan – that’s it. Nothing else is free. CEL diagnosis can be time-consuming, and you should charge accordingly. So, don’t be shy. Tell Mr. Smith tracking down his problem could take an hour, maybe more, and that you can’t work for free. Neither can your techs. If he understands the concept that time is money, he’ll pony up the cash for diagnostic time. 

And the check engine light a great opportunity to include an interactive service walk-around, WITH your customer, now that we're at their vehicle!

If you’re looking to bump up your sales (and what living, breathing service advisor isn’t?) start implementing these CEL strategies at your shop. You’ll be surprised how much revenue that unassuming check engine light can bring in.