2023 Jeep Wrangler PCM Update for MIL & Misfire DTCs

Owners of 2023 Jeep Wrangler vehicles equipped with the 3.6L V6 24V VVT Engine UPG 1 W/ESS (Sales Code ERC) may experience a range of engine performance issues, often accompanied by a lit "Malfunction Indicator Lamp (MIL) illumination". This includes common problems such as misfires, rough idle, and even messages like "Service Transmission" appearing in the instrument cluster. Technical Service Bulletin (TSB) 18-046-26 provides a software update for the Powertrain Control Module (PCM) to resolve these concerns.

This bulletin applies to vehicles sold in North America, South America, Enlarged Europe, China, India & Asia Pacific, and the Middle East & Africa markets.

Symptoms

If your 2023 Jeep Wrangler is affected, you might notice one or more of the following symptoms:

• "Malfunction Indicator Lamp (MIL) illumination" on the dashboard.
• The vehicle has a rough idle.
• The engine has a miss.
• Noisy valvetrain.
• A "Service Transmission" message in the Instrument Panel Cluster (IPC) due to clutch slip detection with the transfer case in neutral.
• Clutch is overheating or slipping on engagement.
• Inability to accelerate uphill.
• The vehicle does not start.
• The vehicle is stuck in limp-home mode.
• The engine runs rough.

Some customers might also experience wheel spin or traction loss, which the PCM could misinterpret as excessive clutch slip, leading to an IPC message to prevent potential clutch damage. If you are experiencing these issues, particularly a "Malfunction Indicator Lamp (MIL) illumination" or a "Service Transmission" message, your 2023 Jeep Wrangler MIL P0300 issue may be resolved by this TSB.

Fault Codes / DTCs

These symptoms are typically accompanied by one or more of the following Diagnostic Trouble Codes (DTCs):

• P0300 - Multiple Cylinder Misfire (Active or Stored status set during cold start catalyst heating)
• P0301 - Cylinder 1 Misfire (Active or Stored status set during cold start catalyst heating)
• P0302 - Cylinder 2 Misfire (Active or Stored status set during cold start catalyst heating)
• P0303 - Cylinder 3 Misfire (Active or Stored status set during cold start catalyst heating)
• P0304 - Cylinder 4 Misfire (Active or Stored status set during cold start catalyst heating)
• P0305-00 - Cylinder 5 Misfire (Active or Stored status set during cold start catalyst heating)
• P0306-00 - Cylinder 6 Misfire (Active or Stored status set during cold start catalyst heating)
• P08A6 - Gear Lever Position Sensor System - Multiple Sensor Correlation
• P152F - Engine Hood Switch 2 / Engine Hood Switch 1 Correlation
• P1129 - Closed Loop Fueling Not Achieved - Bank 2 Upstream
• P0152-02 - O2 Sensor 2/1 Circuit High
• P0158-02 - O2 Sensor 2/2 Circuit High
• P2504 - Charging System Output High
• P0563 - Battery/System Voltage High

Diagnosis

To diagnose these issues, technicians will use a Scan Tool (wiTECH) along with the appropriate Diagnostic Procedures available in DealerCONNECT/Service Library. They will verify that all related systems are functioning as designed. If any DTCs or symptom conditions other than those listed in this bulletin are present, they should be recorded and repaired before proceeding with the TSB's repair procedure.

Important Warnings

Owners should be aware of specific instructions for the repair process:

• Do not allow the charging voltage to climb above 13.5 volts during the flash process. A battery charger must be installed to ensure battery voltage does not drop below 13.2 volts during the software update.
• If this flash process is interrupted/aborted, the flash should be restarted.
• For SA market only, after applying this TSB, it is not necessary to send DID-I or DID-A.

Repair Procedure Summary

The resolution for the 2023 Jeep Wrangler MIL P0300 and related issues involves reprogramming the Powertrain Control Module (PCM) with the latest available software. This update, detailed in TSB 18-046-26, also includes a software enhancement that commands engine oil pump operation to high-pressure mode when the engine oil is cold. This improvement is designed to enhance valvetrain component durability.

The repair process includes:

1. Connecting a battery charger to maintain stable voltage (between 13.2 and 13.5 volts) during the flash process.
2. Reprogramming the PCM using the wiTECH Diagnostic Application with the newest software. If any issues arise during this step, the technician will submit a ticket to the Helpdesk.
3. Clearing all DTCs that may have been set in any module due to the reprogramming process. The wiTECH application will automatically present and allow clearing of all DTCs after the flash.

Required Tools or Parts

The primary tool required for this service is a wiTECH or equivalent diagnostic scan tool.

Owner Action

If your 2023 Jeep Wrangler is exhibiting any of the symptoms or DTCs mentioned, you should schedule an appointment with your authorized Jeep dealer. The dealer will perform the necessary diagnostic checks and apply the PCM software update as outlined in TSB 18-046-26. This repair is reimbursable within the provisions of your vehicle's warranty.

Superseded Bulletins

This bulletin, TSB 18-046-26, supersedes previous Technical Service Bulletins 18-041-24, dated May 03, 2024, and 18-090-25, dated October 03, 2025. These older bulletins should be removed from your files. The current revision includes additional DTCs, customer symptoms, software enhancements, market applicability, and updated labor operation and repair procedure notes.

NHTSA ID: 11031451