2024 BMW X1/X2 FC 034AEF Exhaust Cold Start Not Controllable

BMW has released Service Information Bulletin (SIB) 12 03 24, Revision 6, dated February 12, 2026, to address an "Engine Malfunction Warning" and a specific diagnostic trouble code (DTC) in certain 2024 BMW X1 and X2 models. This bulletin supersedes an earlier version of SIB 12 03 24 from February 2026.

The issue primarily affects vehicles equipped with B48P and B48R engines, specifically the U11 X1 Sports Activity Vehicle and U10 X2 Sports Activity Vehicle. The problem stems from a DME (Digital Motor Electronics) calibration error, which can be resolved through a software update.

Symptoms

Owners of affected 2024 BMW X1 or X2 vehicles may observe an "Engine Malfunction Warning" illuminated on the instrument cluster. This warning is accompanied by the storage of a specific fault code in the DME system.

Fault Codes / DTCs

The primary fault code associated with this issue is:

• FC 034AEF: "Exhaust Cold Start, Not Controllable"

Diagnosis / Trigger Conditions

When the "Engine Malfunction Warning" appears and the fault code FC 034AEF is stored in the DME, it indicates an underlying DME calibration error. This condition specifically relates to the exhaust cold start process, which is not functioning as intended due to the calibration issue.

Important Warnings

BMW has issued several critical advisories for technicians and owners regarding this service action:

• The vehicle's I-level must be 25-11-560 or higher before programming begins. This is crucial to prevent potential WAVE failures during the update process.
• This specific patch is designed only to address the FC 034AEF Exhaust Cold Start, Not Controllable fault.
• Always connect a BMW-approved battery charger/power supply (refer to SI B04 23 10) when performing programming to maintain stable voltage.
• With ISTA 4.57.3x, the target I-level U006-26-03-527 is expected to be activated online from October 2, 2026, and will be available for download during the programming session.
• After downloading the online I-level, the target I-level displayed will change to U006-26-03-527.
• Technicians will be prompted to choose "Activate online integration level". This prompt will only appear until the future release of ISTA 4.58.2x. If programming for another reason, technicians should use the "Continue" tab, and ISTA will use the latest I-level prior to the patch.
• In some cases, the prompt to activate the online I-level may not appear. Technicians will then need to manually select the DME for programming and coding. After selecting "execute measures plan," the prompt should appear. If issues persist, checking or refreshing the ISTA login is advised.
• The programming must be performed using the I-levels specified in the bulletin or any later version.

Repair Procedure Summary

The repair for the 2024 BMW X1 FC 034AEF issue involves an online patch activation using the ISTA diagnostic system. This procedure is both mobile-friendly and Remote Software Upgrade (RSU) friendly.

1. Preparation: Connect a BMW-approved battery charger to the vehicle and connect the programming system (ISTA 4).
2. Measures Plan: Determine the necessary measures plan within ISTA.
3. Online Activation: When prompted, select "Activate online integration level" to download and apply the required software update. This will update the DME to the target integration level U006-26-03-527.
4. Module Programming: Accept and work through the entire measures plan, ensuring all programmable control modules without the latest software are updated and coded.
5. Post-Programming: Follow any rework lists, perform a vehicle test, and clear any stored fault memory.

Required Tools or Parts

To perform this repair, technicians will need:

• ISTA 4.57.3x: This version of the Integrated Service Technical Application, released January 26, 2026, is required, along with its installed service data package.
• BMW-approved battery charger/power supply: Essential for maintaining stable voltage during the programming process (refer to SI B04 23 10).

Warranty Information

This software solution is covered under the terms of the BMW New Vehicle Limited Warranty for Passenger Cars and Light Trucks, or the BMW Certified Pre-Owned Program. The repair code for this procedure is 1136019900, which is generally described as addressing a "Camshaft adjusting unit (VANOS) Fault code stored in diagnosis fault code memory (no warning lamp)" (though applied here for the DME calibration). Labor operations include:

• 00 00 006 or 00 00 556: Carrying out vehicle test.
• 61 21 528: Supporting voltage of the vehicle electrical system / recharging vehicle battery.
• 61 00 006* or 00 58 500*: Diagnosis worktime.
• 61 00 730: Program/encode control unit(s), including deleting fault memory.

If multiple control modules fail during reprogramming, any necessary consequential repair work procedures should be claimed under the repair code, along with corresponding labor operations and flat rate unit allowances.

Owner Action

If you own a 2024 BMW X1 or X2 and experience an "Engine Malfunction Warning" along with the FC 034AEF fault code, contact your authorized BMW dealer. They can diagnose the issue and perform the necessary software update as outlined in SIB 12 03 24.

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Source: NHTSA ID 11028920