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Jeep Cherokee Check Engine Light Diagnostic: (Easy Tips)

What should you do when you’re enjoying a backcountry cruise in your Jeep Cherokee and the check engine light suddenly illuminates? Continue reading to learn about the most common causes of the check engine lights coming on in a Jeep, and how you can proactively save money dealing with it.

What Causes A Jeep Cherokee Check Engine Light to Come On?

The warning lights on your Jeep Cherokee are messengers that display useful information about the operational state of your vehicle.

Beginning in the 1980s, automotive manufacturers started installing onboard diagnostics (OBD) systems in vehicles. These systems continuously monitor all under-the-hood happenings via dozens of sensors placed throughout the engine and its components.

The sensors of an OBD system collect information about the vehicle’s current state and send it back to the electronic control unit (ECU). If a sensor “tells” the ECU that something is wrong with the engine, the ECU creates a warning light to display a specific diagnostic trouble code (DTC).

Let’s continue learning about how to communicate better with a Jeep Cherokee by understanding its diagnostic warnings.

Different nuances for different Jeep Cherokee engines

Understanding what the check engine warning lights are telling you depends on when your Jeep was manufactured. Before the mid-80s, there were no warning lights on vehicles because there were no OBD systems.

Some vehicles had a single warning light that typically read, “ENGINE” or “TROUBLE,” which didn’t yield any specific information about what was actually wrong, just that something was.

Onboard diagnostics for Jeep Cherokees from the mid-80s until 1996

From the middle of the 1980s through 1996, auto manufacturers installed the earliest OBD systems. These older systems are now typically referred to as “OBD-1” to differentiate them from their newer counterparts.

If your Jeep was made during this period, and your check engine light illuminates, you’ll just need a pen and paper to jot down the DTCs.

You can do that by inserting the key into the ignition, and then, without starting the Jeep engine, turn the key ON-OFF-ON-OFF-ON, quickly, within 5 seconds.

Then, you’ll see the check engine light begin to blink, displaying specific diagnostic trouble codes. DTCs for these years of Jeep Cherokees are two digits, ranging from 11 to 77. The code will flash once, then pause, and then flash again.

More than one code may display in succession, each blinking twice and progressing to the next. Write them down and research their meanings via various online resources.

DTCs for Jeeps from 1996 onward

Starting in 1996, automobile manufacturers began using new and improved diagnostics systems, referred to as OBD-2, which send much more detailed information to the ECU. Modern DTCs begin with an alphabetic letter, and then are followed by either 3 or 4 numbers, and then another letter.

There are hundreds of possible diagnostic trouble codes, far more than is feasible to watch flash and write down for research. Learning the codes requires an OBD-2 reader (more on this below).

Common Problems Associated with a Check Engine Light Jeep Cherokee

A check engine light coming on in a Jeep Cherokee can indicate numerous possible problems. Some may seem trivial, but it’s important to remember that these warning lights are just that: warnings.

It’s smart to heed these warnings before the small issues at hand become larger, more complex, and more costly problems. So, let’s review 5 of the most common reasons why a Jeep’s check engine light comes on.

Defective or loose fuel cap

This would be the best-case scenario when a check engine light comes on. If you’re lucky, you just need to tighten the cap. Or it might be defective and need replacing.

Oxygen sensor malfunction

An O2 sensor is relatively inexpensive and simple to replace. This DTC is often overlooked because the engine’s performance is only minorly affected.

Bad spark plug wires

If your plug wires need replacing, you’ll likely find performance to be sacrificed. Your Jeep will run rough and not have as much power as it should.

Catalytic converter issues

The catalytic converter on your Cherokee converts carbon monoxide (CO) into carbon dioxide (CO2). If your converter fails, your entire emissions system will operate ineffectively (and toxically).

Defective ignition coil

If your Jeep’s ignition coil is on the fritz or defective, you’ll know it right away. Common signs include reduced power, toxic emissions, rough idling, repetitive misfiring, and failure to even start.

How to Save Money When Dealing With A Check Engine Light Jeep

Of course, the best plan for dealing with check engine lights coming on in your Jeep Cherokee is to ensure proper routine maintenance and repairs.

Have regular oil changes, tire rotations, and other common maintenance tasks performed, or take care of them yourself. An ounce of prevention…

As mentioned above, it requires an OBD-2 reading device to understand the diagnostic trouble codes displayed in a Jeep that’s from 1996 or after.

These compact devices are inexpensive, typically less than $100 for a basic model that will suffice for the typical Jeep owner’s needs. Buying one of these is a good idea because it saves you from having to go to a mechanic to learn what your DTCs mean.

Remember that checking and understanding what your Jeep Cherokee’s check engine lights are telling you is very important. You’ll save a lot of worry and money in the long run by addressing all warning light issues promptly. It’s not wise to ignore them and continue driving anyway.

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