Blog Car Care Advice What Does the Jeep Check Engine Light Mean + How to Fix?
Car Care Advice

What Does the Jeep Check Engine Light Mean + How to Fix?

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Most car enthusiasts love Jeep cars for their powerful off-road experience and reliability in challenging terrain. 

Imagine this: 
You’re trying to push the limit of your rig when your Jeep Check Engine Light comes on. 

Not the most powerful feeling, right? 
More so because the Jeep Check Engine Light can indicate anything from a loose gas cap to a misfire. 

But don’t worry!
We’ll help you overcome the fear of the unknown. 

Stick with us as we unravel what causes the Jeep Check Engine Light to light up, how you should deal with it, and more. 

This Article Contains 

Let’s decode the Jeep CEL!

What Causes the Jeep Check Engine Light to Turn On?

Sensors are a staple element in every modern vehicle to keep tabs on car systems, and that includes your Jeep Cherokee, Jeep Wrangler, and so on. Whenever your car’s Electronic Control Unit (ECU) detects any error through these sensors, it illuminates the Check Engine Light (CEL Light) on your dash and registers a Diagnostic Trouble Code. 

Even though there could be countless reasons for this warning light to come on, here are a few common ones: 

1. Loose Gas Cap 

More often than not, a loose or missing gas cap can activate the Check Engine Light on your Jeep’s dashboard. The gas cap stops gasoline fumes from being released into the atmosphere and prevents dirt and other contaminants from entering the fuel delivery system. 

But if you continue driving with a loose or broken gas cap, it could allow fuel vapors to escape, reducing the fuel pressure and affecting the fuel economy down the line. 

2. Faulty Oxygen Sensor 

The oxygen sensor (O2 sensor) measures the residual oxygen in your exhaust system and helps the ECU produce the right air-fuel mix for combustion. However, prolonged exposure to hot exhaust gases can cause these sensors to malfunction.

As a result, the faulty oxygen sensor will make your ECU supply too much or too little fuel to the combustion chamber, leading to misfires, engine stalling, poor acceleration, and an illuminated Check Engine Light. 

3. Faulty Mass Airflow Sensor 

The mass airflow sensor (MAF sensor) affects how much air enters your engine for combustion. But constant exposure to particle-rich air can sometimes damage this sensor, causing it to misread the airflow. This can lead to rough idling, trouble starting, and an active Check Engine Light. 

4. Worn Spark Plugs or Spark Plug Wires 

Spark plugs help ignite the air-fuel mix inside your Jeep’s combustion chamber. However, like every car part, spark plugs and their wires can wear out with use, causing the engine to misfire and activate the CEL light. It can also affect your car’s performance to the extent of not letting your engine start at all

If you continue driving with faulty spark plugs or worn spark plug wires, you can end up damaging your catalytic converter, which is costly to repair.

5. Failing Catalytic Converter 

The catalytic converter is a critical part of your exhaust system. It helps break down harmful emissions into carbon dioxide, nitrogen, and water vapor.

However, your catalytic converter can clog without proper maintenance, preventing it from converting harmful emissions (exhaust gases). This can trigger your engine light and affect engine performance by causing it to overheat. It’s also likely that you’ll fail an emissions test. 

6. Vacuum Leak 

Gasoline engines need a vacuum environment to control the engine RPMs. If there’s a vacuum leak through any hose or gasket, your engine won’t start or will lead to higher RPMs at idle.

Since there’s no specific warning light for a vacuum leak, the ECU will activate the Check Engine Light and register a Diagnostic Trouble Code, informing you that your engine has a problem. 

Now you know what could be causing your Jeeps Check Engine Light to come on. Let’s see what you need to do next. 

What To Do If Your Jeep Check Engine Light Turns On?

The engine light can come up on your dash in different patterns, each indicating the gravity of the situation. Here’s what a Jeep owner needs to do under each circumstance: 

1. CEL Illuminates Under Certain Conditions

If your engine light comes on intermittently, look for any other performance changes in your vehicle. If you can feel a consistent decrease in engine performance, your vehicle may have entered the “limp mode” to prevent further damage. In that case, it’s best to have your vehicle towed to the nearest service station to get the engine light and the trouble code diagnosed using an OBD ii scanner. 

2. The Engine Light is Constantly On

A steadily illuminated Check Engine Light is usually not an alarming situation. It indicates that your Jeep’s onboard diagnostics (OBD ii) has identified an issue and registered related fault codes.  Your vehicle may seem to run fine, but it’s best to diagnose the CEL light and the related trouble code at the earliest using a scan tool. 

3. Flashing Check Engine Light 

If you have a consistently flashing Check Engine Light, it indicates a major issue requiring immediate attention. Ignoring a flashing engine light can lead to severe and irreversible engine damage. To avoid this, you should pull over ASAP and call for roadside assistance. 

Wondering how much it’ll cost to diagnose the issue?
Keep scrolling!

How Much Does a Jeep Check Engine Light Diagnosis Cost?

As mentioned, the Check Engine Light can come on for a myriad of reasons, right from a loose gas cap or a faulty plug, to a failing catalytic converter.

In either case, a proper diagnosis using an OBD ii scanner and engine test is necessary, which could cost anywhere between $80-120, depending on your car’s make and model. Once a mechanic diagnoses and fixes the underlying problem, the Check Engine Light should turn off itself. 

But if they forget to reset it, you might have to do it yourself.
Let’s find out how. 

How to Reset the Check Engine Light

If your mechanic has fixed the underlying problem, but the light is still on, here are the steps to reset it: 

  1. Open your Jeep’s hood and locate the battery. 
  2. Disconnect the battery’s negative cable.
  3. Wait 20 minutes and reconnect the negative cable to your car’s battery. This will reset the car’s computer on any modern vehicle and turn off the engine light. 

Note: You might have to drive 50 miles or more to reset the ECU if you own an older vehicle. 

Final Thoughts 

Whether you own a Jeep Cherokee or a Jeep Compass, the Check Engine Light can be the most ambiguous light on your car’s dash. But you shouldn’t ignore it at any cost. And if it’s a flashing light, it certainly requires immediate attention.

Don’t have time to take your car for a diagnosis?
Why not have an expert from AutoNation Mobile Service come to your driveway to fix it? 

We are a reliable mobile vehicle repair service available seven days a week. All our repairs are performed by expert technicians, backed by a 12,000 miles | 12-month warranty.

Need help with other repairs like an oil change, bad battery, or air filter replacement? 
We can fix that too! 

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