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3.0 Duramax Diesel with LZ0 Possible Leak at Intake Manifold

A technical service bulletin #22-NA-128 addressing a malfunction indicator lamp (MIL) illumination issue has been updated to now include the LZ0 Engine whereas before the bulletin only applied to the LM2. This bulletin specifically pertains to several Cadillac, Chevrolet, and GMC models spanning the model years 2022 to 2025. The bulletin highlights the diagnostic trouble codes (DTCs) P0172, P026D, P2459, and P2A00, which are indicative of a leak in the intake manifold. This article aims to delve into the issue, explore its causes, and provide a comprehensive guide on how to correct it.

Affected Vehicles (w/ 3.0 Duramax Diesel Engine)

The models involved in this issue include:

Cadillac Escalade (2022 - 2024)

Chevrolet Silverado (2022 - 2025)

Chevrolet Suburban / Tahoe (2022 - 2024)

GMC Sierra (2022 - 2025)

GMC Yukon (2022 - 2024


The Condition and Diagnostic Trouble Codes

Owners of the affected models may notice the MIL illuminated on their vehicle’s dashboard. Upon inspection, technicians might find one or more of the following DTCs set in the Engine Control Module (ECM)

  • P0172: Fuel Trim System Rich

  • P026D: Fuel Injection Quantity Too High

  • P2459: Particulate Filter Regeneration Frequency

  • P2A00: Heated Oxygen Sensor Performance

Cause

The primary cause of this issue is identified as a leak at the intake manifold. This can lead to improper air-fuel mixture ratios, excessive fuel injection, issues with the particulate filter regeneration process, and problems with the heated oxygen sensor's performance.


Correction

To rectify this issue, technicians should follow these steps:

  1. Component/System Leak Test: Using the procedures outlined in the Service Information (SI) or bulletin PIP5684, technicians can perform a leak test to identify the presence of a leak in the intake manifold.

  2. Replace the Intake Manifold: If a leak is detected, the intake manifold must be replaced. Technicians can refer to the "Intake Manifold Replacement" procedure in SI for detailed instructions.


Important Compliance Notice

Service agents are reminded to comply with all applicable laws and regulations related to handling, deploying, preparing, classifying, packaging, marking, labeling, and shipping dangerous goods. In case of a conflict between the bulletin procedures and local laws, the latter must be followed.


Service Procedure and Parts Information

Technicians should follow the detailed service procedure for intake manifold replacement provided in the SI. The required part for this repair is the intake manifold with the part number 55511544.


The illumination of the MIL and the associated DTCs P0172, P026D, P2459, and P2A00 in select GM vehicles point to a common issue—a leak in the intake manifold. By adhering to the outlined diagnostic and corrective procedures, technicians can effectively resolve this issue, ensuring that the vehicles operate smoothly and efficiently. Vehicle owners experiencing this problem should promptly seek service to prevent further complications and maintain optimal vehicle performance.


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