Jeep Wrangler JK: How to Reset Check Engine Light
A Check Engine light, often referred to as a Malfunction Indicator Lamp, is displayed to warn the driver that the computer senses a fault somewhere in the vehicle. While the Check Engine light may be an eyesore, it is best to diagnose the root cause of the problem before attempting to turn the light off.
This article applies to the JK Jeep Wrangler (2007-Present).
The On-Board Diagnostics (OBD) system incorporated into modern vehicles is able to monitor various powertrain and emission parameters to ensure the car is running properly. The OBD-II system is seamlessly integrated into the vehicle and its advanced functioning is often never noticed by drivers. That being said, when the system monitors an abnormality in the engine, transmission, or emission control system, the check engine light will illuminate to indicate that one of these systems needs attention. With the use of a code reader or scan tool, individuals can quickly identify the source of the problem and, once fixed, reset the Check Engine light. Similarly, if your are the patient type, the JK's built-in code reader can display fault codes, but resetting the Check Engine light will reside with the computer after it has determined that the fault has been fixed. This article will give an overview of how to reset the Check Engine light on the 2007 to 2016 JK Jeep Wrangler.
Materials Needed
- OBD-II code reader or scan tool (optional)
- Keys
Step 1 – Read diagnostic fault codes
Whenever the Check Engine light illuminates, scanning the computer for fault codes can give insight into the source of the problem.
Scan Tool Method
- Connect your OBD-II scan tool or code reader to the diagnostic port located under the driver's side dash.
- Once the code reader has been plugged in, turn the ignition to the ON position without starting the car.
- Read the fault codes to determine the cause of the Check Engine light. Depending on the make and model of your scan tool or code reader, you may be able to view freeze frame data or perform various component function tests.
Key Method
- Turn the key to the ON position without starting the car.
- Push the key into the ignition cylinder (towards the steering column) and, while holding it in, turn the key to the OFF position and back to the ON position three times. Be sure to end with the key in the ON position.
- If done correctly, all of the dash lights will illuminate and the display normally reserved for the odometer reading will appear as a series of six dashes.
- The dashes will be momentarily be followed by any stored fault codes.
- After all fault codes have been displayed, the message will read "-d0ne-" and the key can be turned off.
Pro Tip
While it is nifty that Jeep has included a built-in code reader, it cannot be used to manually reset the Check Engine light.
Step 2 – Replace faulty component(s)
After gathering the stored fault code(s) and properly diagnosing the source of the problem, proceed with replacing the faulty component(s).
Pro Tip
Resetting the Check Engine light without replacing the faulty component(s) is only a temporary fix. Once the vehicle is driven and its drive cycle has completed, the faulty component will again trigger the Check Engine light.
Step 3 – Reset check engine light
After replacing the faulty component(s), you may once again connect your scan tool or code reader to the diagnostic port and proceed clearing all fault codes. Once the fault codes have been cleared, the vehicle can be started to ensure the Check Engine light is off.
Figure 6. Erasing fault codes. 
Figure 7. Gauge cluster with Check Engine light now reset.
Pro Tip
While manually clearing fault codes will quickly reset the Check Engine light, the light can also reset after the vehicle has completed a drive cycle and the computer determines that the recently replaced component(s) is functioning within spec.
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