LZ0 Pickup Truck Calibration Releases (Feb 6, 2026)

GM has released Bulletin # 26-NA-052, addressing multiple Malfunction Indicator Lamp (MIL) concerns on 2026 model year LZ0-equipped pickup trucks. The fix is a software update to the Engine Control Module (ECM)—no parts replacement required.

Affected Vehicles

Models

• 2026 Chevrolet Silverado 1500

• 2026 GMC Sierra 1500

Engine

• 3.0L Turbo Diesel (LZ0)

Transmission

• All

Region

• North America

  
  

Customer Complaint

Owners may report:

• MIL / Check Engine Light illuminated

• In some cases, drivability concerns or warnings tied to fuel pressure or emissions performance

  
  

DTCs Covered by This Bulletin

This calibration update addresses the following trouble codes:

• P1498 – Particulate Matter Control Module Internal Supply Voltage Circuit

• 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

• P226D – Diesel Particulate Filter (DPF) Deteriorated Substrate

• P2264 – Water in Fuel Indicator Sensor Circuit

• P2C7A – NOx Catalyst 2 Efficiency Below Threshold

This is a wide mix of fuel system, aftertreatment, and sensor rationality codes, which strongly suggests calibration logic—not hard component failures—was the root cause.

GM’s Root Cause Explanation

According to GM, these conditions may occur due to ECM software behavior that can incorrectly interpret sensor data or operating conditions, triggering faults and, in some cases, forced engine shutdown strategies.

In other words: The truck may be doing exactly what it’s told, but the logic itself needed refinement.

The Fix

Correction

• Reprogram the Engine Control Module (K20) with the latest calibration using SPS2

Important Notes

• If the ECM already has the latest software, no further repair is required.

• This bulletin is software-only — no parts are replaced.

• Programming must be performed by a certified repair facility with proper GM training and equipment.

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Warranty Information (Important for Owners)

• Labor Operation: 2810075

• Description: Engine Control Module Reprogramming with SPS

• Labor Time: Use published labor operation time

• Parts Required: None

This repair is warranty-eligible, assuming the vehicle is still within coverage and the fault is present or documented.

What Owners Should Know

From a technician standpoint, here’s why this bulletin matters:

• These codes do not automatically mean you have bad injectors, a failing DPF, or contaminated fuel

• Forced shutdown fuel pressure codes (P228A/B) can be especially alarming—but GM is acknowledging that software logic can falsely trigger them

• If you’ve been chasing intermittent MILs with no clear mechanical failure, this update should be checked first

What I would do:If you have any of the listed codes—active or in history—verify ECM calibration level before authorizing parts replacement.

Bottom Line

Bulletin # 26-NA-052 is a significant clean-up calibration for early 2026 LZ0 trucks. It targets a cluster of fuel system and aftertreatment DTCs that can create unnecessary concern, dealer visits, and even shutdown events.

If your 2026 Silverado or Sierra 1500 has an LZ0 and the check engine light has been acting up, this update should be on your radar.