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The Dangers of Ignoring Check Engine Lights: A Truck Driver’s Guide

July 5th, 2024

Greg Wentworth

Greg Wentworth

Greg joined the ATS team in 2019. He’s spent more than 30 years working on all types of trucks and trailers and spent 29 years as a dealer technician. He carries several certifications from different original equipment manufacturers (OEMs). His favorite part of his role as a technical trainer and quality assurance insurance inspector is helping the technicians learn and build their own knowledge base.

As a truck driver, you know your rig is more than just a vehicle — it's your livelihood. If you’re an over-the-road (OTR) driver, It’s your home away from home. It’s the tool you need to do your job and bring home money to support your family. 

One of the most critical aspects of keeping your truck in top shape is paying attention to the warning lights on your dashboard.

Ignoring these signals can lead to serious consequences, not only for your truck but also for your wallet and your schedule. 

Unfortunately, though, some drivers do ignore the check engine light for too long. We see this all the time in the shop at Anderson Trucking Service: A catastrophic engine failure that could’ve been prevented with an earlier trip to the shop. 

Ignoring your check engine light can result in: 

Let’s dive into the adverse effects of ignoring a check engine or warning light and why addressing these issues promptly is essential.

3 Reasons You Shouldn’t Ignore Your Check Engine Light

Letting the light stay on unchecked for a few days can be tempting, but days turn to weeks and your truck will suffer for it.

Ignoring your service engine light can lead to progressive damage. 

Reason #1: Progressive Damage and Warranty Risks

When a warning light illuminates on your dashboard, it's a clear sign that something needs attention. Continuing to drive with a warning light can cause progressive damage to your truck. For instance, if the root cause of the warning is something like a fuel injector failure, prolonged driving can exacerbate the issue, leading to extensive and costly damage.

Shops and original equipment manufacturers (OEMs) keep a close eye on truck maintenance. Warranty coverage is often tied to proper upkeep. If the truck wasn’t properly maintained (it wasn’t taken in for regular maintenance intervals), the OEM can deny warranty coverage. 

So, if it’s evident a truck was driven for an extended period with a warning light on, the manufacturer may deny warranty claims. This means you could be left footing the bill for repairs that would otherwise have been covered. 

In other words, ignoring that pesky service engine light might lead to paying out-of-pocket for major repairs, which can quickly add up.

Learn more about warranty coverage and why (documented) maintenance is important.

Reason #2: Reduced Power Output

When you see your check engine light go on, it’s tempting to think it’s something minor that can wait and be fixed easily down the road. 

But sometimes, certain fault codes don’t just signal a problem — they actively reduce your truck's power output to prevent further damage. This reduction can be gradual, but if ignored, it can lead to a full derate in power and a significant reduction in road speed, sometimes bringing your truck down to a crawl at 5 mph.

Imagine having your service engine light on for days but you’ve ignored it. You’re on a tight delivery schedule and suddenly your truck’s power output and speed are significantly reduced. Within a few minutes, your truck is incapable of maintaining highway speeds. There’s no way you'll make the delivery, much less make it to the shop without assistance.

If your truck reaches this critical point and requires towing, the costs can be substantial. And if your warranty coverage is denied, the costs add up even further. Depending on your company and the type of driver you are (company driver vs. independent contractor), these costs may come directly out of your pocket. 

Avoiding this situation is as simple as addressing warning lights when they first appear.

Three ATS trucks parked in front of a J.B. Hunt facility.

Reason #3: Loss of Oil Pressure and Engine Damage

Daily checks of engine fluid levels are a must. If the oil level drops too low due to a leak or consumption, and you continue driving without addressing it, the engine could suffer severe damage. 

Warning lights for low oil pressure are critical indicators that immediate action is needed. Repeatedly restarting your engine in this state can lead to catastrophic engine failure — leading to a much bigger mess on your hands.

Truck manufacturers track occurrences of low fluid levels and the corresponding fault codes. When you ignore these warnings, the data logs show the frequency and duration of the issue. This information is often used to deny warranty claims, potentially leading to expensive repairs you have to pay for yourself. 

What to Do When the Check Engine Light Goes On

If your check engine light does go on while you’re driving, try to get to a safe location to pull over, such as a rest stop or truck stop. If the nearest one isn’t close, you may need to pull over onto the side of the road. 

Get as far onto the side of the road as you can and turn on your flashers. Put out your safety triangles to warn oncoming traffic that you’re pulled over. Be careful while getting out of the truck; look for oncoming traffic.

Then, you’ll want to call your trucking company. 

Most modern trucks provide the ability to read active fault codes directly from the dash display. These codes usually come with a description or number that can be further investigated. A quick call to your dealer, your trucking company’s road service, or even a simple Google search can provide insights into the severity of the problem and the necessary steps to fix it.

Your company will be able to advise you on next steps — whether that means driving to the nearest shop, getting a tow, or getting routed back to a terminal or headquarters.

Related: What to do if your ATS truck breaks down

Dashboard with warning lights illuminated.

Take Action, Save Money, and Stay on the Road

Ignoring a check engine or warning light is not just a minor oversight — it’s a decision that can lead to significant and costly consequences. Not only can you end up with more damage to your truck, but you may void your warranty by not properly maintaining the truck. If you cause further damage to your truck, shop bills can add up quickly — especially if a tow is involved and you can’t get it fixed at your carrier’s shop. Fixing your truck on the road is a lot more expensive.

By addressing issues as soon as they arise, you can avoid progressive damage, maintain power output, protect your engine, and keep your warranty intact.

Stay proactive, take those warning lights seriously, and keep your rig — and your livelihood — running smoothly.

There are some other signs a breakdown may be near. Look for these signs that your truck may be in trouble.