GM Issues New Calibration Bulletin 26‑NA‑090 for 3.0L LZ0 Duramax Pickups

The latest GM service bulletin # 26-NA-090, released on March 12, 2026, provides key information on calibration releases for the 3.0L Duramax diesel (LZ0) in 2025 pickup trucks. This is an informational bulletin guiding dealers on available ECM (Engine Control Module) software updates to address illuminated Malfunction Indicator Lamp (MIL) concerns.

Affected Vehicles

• Chevrolet Silverado 1500 (2025 MY) with 3.0L Diesel (LZ0), all transmissions

• GMC Sierra 1500 (2025 MY) with 3.0L Diesel (LZ0), all transmissions

These apply to vehicles in regions including North America, Middle East, various South American countries (Mercosur and West), South Korea, and Philippines.

Customer Concern

Some owners may report the MIL (check engine light) coming on.

Potential Causes

This can stem from one or more of the following Diagnostic Trouble Codes (DTCs):

• P060C – Control Module Main Processor Performance

• P062B – Control Module Fuel Injector Control Performance

• P1498 – Particulate Matter Control Module Internal Supply Voltage Circuit

• P226D – Particulate Filter Deteriorated Substrate

• P228A – Fuel Pressure Regulator Control - Forced Engine Shutdown

• P228B – Fuel Pressure Regulator 2 Control - Forced Engine Shutdown

• P228C – Fuel Pressure Regulator Control Performance - Low Pressure

• P228D – Fuel Pressure Regulator Control Performance - High Pressure

• P24C7 – Particulate Matter Sensor Temperature Circuit Performance

These DTCs often relate to fuel system control, injector performance, aftertreatment (DPF/particulate matter) issues, or pressure regulation in the diesel system.

Recommended Correction

1. First, check for any open campaigns requiring an ECM update.

2. If no campaigns apply, check for and apply any available ECM calibration updates via GM's Service Programming System (SPS).

3. If no updates are available or the issue persists after updating, proceed with standard diagnostics per GM Service Information (SI).

Important Note: No parts are required for this repair—it's software-only unless further diagnostics reveal a hardware issue.

Warranty Coverage

ECM calibration updates (reprogramming) like those referenced in this bulletin are typically covered under the vehicle's New Vehicle Limited Warranty (Bumper-to-Bumper) if the vehicle is still within the coverage period and the update addresses a documented concern.

However, warranty approval depends on the specific situation—dealers will verify if the vehicle qualifies based on mileage, age, and whether the MIL/DTC is present. Preemptive reprogramming (without an active issue) is usually not covered and could be at the owner's expense.

Key Advice for Owners

This bulletin does not mean every 2025 LZ0 truck needs (or qualifies for) a free ECM update. It simply informs technicians that calibrations are available to potentially resolve these specific DTCs when they appear. Do not just take your truck in for a "reprogram" without an actual issue—the vehicle must be experiencing one of these codes (or related MIL illumination) for the update to be considered under warranty in most cases. The calibration may help address software-related contributions to the codes, but it does not guarantee a fix if there's an underlying hardware problem (e.g., a faulty sensor, injector, or particulate filter issue). Dealers should always scan for codes, apply any applicable updates if relevant, and perform full diagnostics if needed.

Important Service Procedure Reminders Dealers must follow all applicable laws for handling any materials (though none are typically involved here). Always prioritize local regulations over bulletin steps if conflicts arise.

This bulletin (Version 1, released March 12, 2026) continues the pattern of ongoing ECM refinements for the LZ0 engine in newer applications, similar to prior releases addressing MIL/DTC clusters in fuel and emissions systems.