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Everything About Jeep Wrangler Check Engine Codes

Most Jeep Wrangler owners have seen the coded engine light blinking either red or amber. Those who don’t know often get terrified of the signals. Well, it’s a part of your dashboard that keeps the performance in check. So what exactly is a Jeep Wrangler check engine code?

The check engine codes in a Jeep Wrangler are mainly diagnostic trouble codes (DTC) or on-board computer diagnostic codes (OBD). It’s a part of the computer system of your Jeep that gives different signals whenever there’s an issue with specific sections of the engine. The code on the dashboard or Odometer has five characters which exact information about the related issue.

So, when you notice the DTC code or the check engine light illuminating continuously, you must intercept the code and take action on those issues.

What Does Check Engine Codes Mean On Jeep Wranglers?

It isn’t very comforting when a tiny light on the dashboard suddenly continues to illuminate. Well, it’s an issue to panic and stop your journey.

These check engine lights are also known as diagnostic trouble codes (DTC). Your vehicle’s electronic control module (ECM) stores these automotive computer codes.

You can also call them on-board computer diagnostic systems (OBD). It controls and monitors vehicles’ performance.

DTC or OBD includes automatic transmission control, ignition timing, implementing stability control, etc. Therefore, the light illuminates and shows the DTC codes whenever there’s unusual activity in vehicle performance.

There are hundreds of check engine codes that represent various problems. But the most common reasons are old batteries, bad spark plugs, O2 sensors, emission control issues, ignition system faults, air or fuel metering problems, computer circuit issues, gas cap problems, transmission issues, etc. You need to know the specific meaning of those codes and act accordingly. 

How Many Check Engine Codes Are There In Jeep Wranglers?

Check engine codes come in five digits; the first number is always a letter. And manufacturers take advantage of it and give codes to every possible problem in your vehicle’s engine.

There can be more than 650 check engine codes in a jeep wrangler. Don’t worry because you won’t need to review the entire list.

You can just read the code and go through the sections. That’s because the first character tells you the overview of the issue, and the second and third one tells you about the specific section.

Therefore, it gets easier to find the specific codes among the hundreds. Once you get the fault details, you can take immediate action.

How Do You Diagnose Jeep Wrangler Check Engine Codes?

To solve the problem, you must understand each DTC code. You have to learn the diagnostic system for your check engine codes. The five-digit code isn’t very tough to intercept. Walk through these simple steps and learn to diagnose yourself:

Step 1: Preparation

To start the process, you will need an OBD scanner. It’s a pretty handy tool with a 16-pin trapezoidal connector, also known as a diagnostic link connector (DLC).

You can connect it to your vehicle to intercept the OBD code. It will come at $30 to $60.

Step 2: Plug The Scanner

It would be best if you found the OBD port to connect the OBD scanner. Each vehicle has a different location for the OBD port. But mostly, it’s situated under the driver side’s dashboard, which is pretty near the pedals.

In some rare cases, you can also find it below the glove compartment or in the center of the dashboard. So, it’s better to check the manual before you start.

Step 3: Start The Ignition

Now it’s time to turn on the ignition. However, never start the engine in the middle of the process. It will provide power to the OBD scanner. The scanner will communicate with the onboard computer of your vehicle.

A message “establishing a link with OBD” will appear when the scanning begins. Check your car’s power connection and ignition if the scanner isn’t working properly.

Step 4: Vehicle Identification Number (VIN) Input

As the OBD codes are specific according to manufacturers, you need to enter the vehicle identification number and engine type into the scanner.

In this way, the scanner will be able to provide you with accurate information about the codes.

Step 5: Navigate The Codes On The Menu

The scanner will start to find the codes. And it would be best if you found the codes from the menu.

You will get an option to choose between pending codes and active codes. The pending codes have already occurred once but haven’t tripped the check engine light.

The codes will go into active mode if the same problem occurs again. Active codes mean the problems are presently causing the check engine light to stay on.

Step 6: Intercept First Character

Now that you have the code, you need to start intercepting. The code consists of five characters, and the first one is to provide an overview of the issue. Here’s how:

  • P = problem with the powertrain system
  • C = problem with the chassis
  • B = problem with the body system
  • U = problem with the network communication system

Step 7: Intercept Second Character

The second character is a digit that signifies whether it’s a manufacturer-specific or generic issue. The specific codes are:

U0, U3, C0, C3, B0, B3, P34-P39, P0, P2 = indicates generic issues.

U1, U2, C1, C2, B1, B2, P30-P33, P1 = indicates manufacturer-specific issues.

Some manufacturers make exceptions because some problems don’t specify the generic issues.

Step 8: Intercept Third Character

The third character is also a digit that provides information on the location of the problem. You will find different interpretation numbers for each issue. such as:

  • 7,8,9 = issues with the transmission
  • 6 = computer output circuit problem
  • 5 = problems with the idle control system and vehicle speed control system
  • 4 = problems with auxiliary emission control
  • 3 = problems with ignition or misfire or injection system
  • 2 = injector circuit problems (fuel and air metering)
  • 1 = problem with fuel and air metering

Step 9: The Final One

The last two digits (00-99) indicate the exact fault. There are thousands of potential faults.

You must read the manual and get a match for your intercepted code to know the exact details. Or you can just search online to find a match. Learn the details of the problem and the techniques to solve it. 

How Do You Read Jeep Wrangler Engine Code Without A Reader?

To read the OBD codes, you will need an OBD scanner. But what if you don’t have any? How can you solve the DTC code problems and run your vehicle smoothly?

Well, it’s possible to read jeep wrangler engine code without a reader or scanner. You can apply two different methods to read the DTC codes. Here’s how:

Method 1: Use The Odometer

With the Odometer, you won’t need any reader or scanner to read the check engine codes. Here are steps to follow to succeed:

Step 1: Reset The Odometer

First, you need to turn on the ignition key. And then press the Odometer’s trip.

After that, reset the buttons. You have to do these three tasks at the same time. Release the trip button, and the Odometer reset after turning on the key.

You will notice the DTC codes appearing on the odometer display. Only then will you know if the process of generating the DTC codes without a scanner has succeeded.

Step 2: Multiple Ignition Key Flips (Optional)

If the reset fails, you need to try again. But this time, you need to switch the ignition key in a sequence of ON-OFF-ON while pressing the reset button and odometer trip simultaneously.

End the action with the ON position of the switch, then release the reset button and odometer trip immediately.

Step 3: Check Odometer Screen

Then, check the odometer screen and look for the DTC codes. Note the code quickly. If there are no codes on the screen, you must go to the next step.

Step 4: Use Jumper Wire Or Paper Clip (Alternative)

Typically, OBD1-supported cars show the DTC codes after applying the mentioned steps, but if you fail, there’s another way that uses a jumper or a paperclip.

You need to turn off your car first. An OBD port is a diagnostic connector underneath the steering wheel. Check the manual for a better understanding of the location.

After that, connect the two terminals on the OBD port with the paper clip or jumper wire. It means you have just created a closed circuit.

Now you need to turn the ignition ON of your car, but don’t crank it. The trouble codes will show up after flashing the engine light.

Step 5: Note And Interpret The Pulse

Now, it’s time to note the engine light codes. Each light represents a digit. Each blink is considered a pulse, and the pause between the pulses refers to the separation between digits.

You need to know that it’s a quick engine light flash when it’s a zero. For example, if the car’s fault code is 21, the light will go like pulse, pulse, pause, and pulse.

After the interpretation, look for the faults and resolve the issues once and for all.

Method 2: Use The Ignition Key

Using the ignition key is probably the easiest way to read the OBDⅠ and OBDⅡ without a reader. Here’s how you do it:

Step 1: Ignition Key Turn On

First, you need to switch ON and OFF your ignition key. And obviously, don’t start the engine during the process.

You must do it 3 to 5 times, so the flipping stops at the ON position. The flipped number depends on your car model.

However, there’s a simple trick. It would help if you observed the dashboard.

When you see all the lights illuminating, stop the ignition. If you crank the engine by any chance, you need to start over to check the engine light codes.

Step 2: Check The Dashboard

The dash lights will turn on for a few moments and eventually turn off, except for the service engine light. Observe the service engine light for a pulse or flash. It will indicate that your car is OBD-Ⅰ.

So, note the flashes originating from the service engine light because it’s your fault or DTC code.

But if the odometer display starts to show engine light codes, it means your car is OBD-II. Note down the codes. However, OBD-II is only applicable for newer vehicles.

Step 3: Read The Code

You need to note the code based on the flash or pulse. This trick is already mentioned in the odometer section. So, use the trick and read the DTC codes.

Step 4: Note And Interpret

After that, you need to check the manual for code description or search on the internet. Each code signifies different problems on different models.

For example, code 16 means problems with the fuel injectors if you own a Honda. On the other hand, fault code 22 means problems with the fuel pump on Nissan.

Is It Okay To Drive When Check Engine Codes Are Stored?

Well, the answer is a bit tricky. That’s because it depends on the severity of the cause. Some codes are just for showing you engine status, whereas, others signals are for some mild to serious engine issue.

For example, driving would be okay if the problem is with the loose gas cap. But when there’s a problem with the transmission, you need to get the jeep for the repairs.

However, it’s also possible to notice the severity with the glow of the check engine lights.

The issue might be scrupulous if the light is glowing at its full potential. And it’s pretty rigid to identify how many miles you can drive with such issues.

Therefore, deciphering the code and learning about the issue is the best option. Then, decide whether to go to the repair shop or drive a few miles.

But when you notice the light is blinking, you should pull over and intercept the code to figure out the problem first.


Check engine codes or DTC codes are not much of a worry as long as you know the codes’ meanings. It’s not tough to learn how to decipher the five-character codes. They are your guide to provide information about your jeep’s performance.

Hopefully, the discussion on the check engine codes of your Jeep Wrangler has provided all the information you need. Check the manual to find the meaning of the codes or search online.

It’s best to learn about the cause and try to solve it rather than ignore it and continue driving. It might prove dangerous for you. Drive safe!

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