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How To Check Diagnostic Trouble Codes On Your Jeep Wrangler JK

Thanks to Jeep and their progression of onboard technology, just about every single part on your new Jeep JK Wrangler is wired up to a computer (BCM, ABS, ECU). And, if anything goes wrong, your Jeep’s computer will make a note of it and/or even let you know about it by illuminating a Malfunction Indicator Light (MIL for short or “check engine light”) icon on your dash. Unfortunately, the MIL or other icons won’t tell you a whole lot other than the fact that your Jeep is having some kind of a problem and unless you take your Jeep into the dealership or have your own OBDII reader handy, you’re pretty much out of luck, right? Wrong. Luck would have it, the Jeep JK Wrangler’s come with an onboard Diagnostic Trouble Code (DTC) reader built right into the dash. You can access the codes by following the 3 simple steps. Once you have the DTC code(s) in hand, check it/them against the list below and you will be able to find out exactly what problems your Jeep is having.

  1.        To check your Jeep JK Wrangler’s DTC codes, simply insert your key into the ignition, turn it to the ‘ON’ position but do not start the engine. Then, push the key into the ignition cylinder and while holding it in, turn it to the ‘OFF’ position and then back to the ‘ON’ position (3) times straight making sure to end with it in the ‘ON’ position. It is important to keep pushing in on the key to prevent it from catching at the different positions along the way.
  2.       If you do step #1 correctly, all your dash lights will illuminate and your odometer will show up as a series of (6) dashes as shown in the pic to the left. If your Jeep JK Wrangler has any logged in any DTC’s, they will be displayed soon after the dashes appear. Write down the DTC(s) and check it/them against the list below to find out what they mean.
  3.       If your Jeep JK Wrangler has not logged in any DTC’s, the dashes on your odometer will be followed by the message ‘-done-’. Turn your key to the ‘OFF’ position and you will in fact be done.

How to Read a DTC


A DTC or Diagnostic Trouble Code is made up of 5 digits the first of which is one of the following letters:

B – Body
C – Chasis
P – Power Train
U – Network

The 2nd digit indicates:

0 – SAE
1 – MFG

The 3rd digit indicates:

1 – Fuel & Air Metering
2 – Fuel & Air Metering
(Injector Circuit)
3 – Injection Systems or Misfire
4 – Auxillary Emissions Control
5 – Vehicle Speed Control
& Idle Control System
6 – Computer Output Circuit
7 – Transmission
8 – Transmission

The last 2 digits indicate:

Fault (00-99)
Special Thanks To Project-JK


2 thoughts on “How To Check Diagnostic Trouble Codes On Your Jeep Wrangler JK

  1. 2013 J/K. I just had a check engine light come on and when I go to check it, no code shows up, just dashes and then says done. Light is still on. Any thoughts?

    • With the engine off, but the ignition turned on, the dash light will be illuminated. If you perform the code check and it doesnt show a code, start the engine and it should turn off. If the engine light is still illuminated with the engine running, it will need to be taken to your local Jeep dealership and connected to their scan tool to find the fault.

      Thank you,
      Eric

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