2021-2024 Jeep Engine Cold Start Rough Idle TSB 09-018-25

Owners of 2021-2024 Jeep Wrangler, Grand Cherokee, and Compass vehicles equipped with either the 2.0L I4 DOHC DI Turbo Engine with ESS (Sales Code EC1) or the 2.0L I4 DOHC DI Turbo PHEV Engine (Sales Code ECX) may experience a Jeep engine cold start rough idle and low coolant levels. This issue is addressed by Technical Service Bulletin (TSB) 09-018-25, which outlines a diagnostic procedure for identifying engine cylinder block porosity.

Symptoms

If your Jeep is affected by this issue, you may notice the following symptoms:

• Rough engine idle when cold starting the engine: The engine may run unevenly or vibrate excessively immediately after a cold start.
• Low coolant level in coolant recovery bottle: You might observe that the coolant reservoir frequently requires topping off, indicating a potential leak or consumption.

These symptoms are often linked to engine cylinder block porosity, which can lead to internal coolant leaks.

Diagnosis / Trigger Conditions

Before any cooling or engine system components are replaced, technicians are instructed to perform a detailed inspection. The diagnostic process for a Jeep engine cold start rough idle involves several steps:

1. Verify Rough Idle: The technician will cold start the engine to confirm if it runs rough initially and then returns to normal operation after approximately 30 seconds.
2. Identify Misfiring Cylinders: If the rough idle is confirmed, the specific cylinder or cylinders experiencing misfire will be identified.
3. Coolant System Pressure Test: The coolant system will be pressurized to 21 psi using a cooling system pressure tester, with the engine at normal operating temperature for 12 minutes. The technician will observe for any pressure decay on the gauge.
4. Borescope Inspection: While the coolant system remains pressurized, a borescope will be used to inspect the affected cylinder(s) for any traces of coolant. The entire perimeter of the bore must be thoroughly checked.

Repair Procedure Summary

If coolant is detected in the affected cylinder(s) during the borescope inspection, it indicates the presence of cylinder block porosity or cracks. In such cases, the recommended repair is to replace the engine long block assembly. Technicians are directed to refer to the detailed service procedures available in DealerCONNECT/Service Library under 'Service Info > 09 - Engine, 2.0L / Engine Assembly / Removal and Installation'.

Required Tools or Parts

To perform the diagnostic procedure outlined in TSB 09-018-25, specific tools are required:

• Tester, Cooling System Pressure (Ref. No. 10447A): Used to pressurize the cooling system and check for leaks.
• Borescope (Ref. No. NPN): A commercially available tool used for internal inspection of the engine cylinders.

Important Warnings

This Technical Service Bulletin 09-018-25 is provided as