Bulletin No.: 25-NA-025

Service Bulletin

Date: February, 2025

TECHNICAL
Subject:

Brand:

Buick
Chevrolet

Malfunction Indicator Lamp (MIL) Illuminated - DTCs P0690, P16B3, and/or
P2420 Set
Model:

Model Year:
from

to

2025

2026

Build Date:
from

Engine:
to

Transmissi
on:

Encore GX
Envista
Trailblazer

LBP

Trax

Involved Region or Country

North America

Condition

Some customers may comment that the MIL is illuminated.
Note: A software issue may cause the DTCs noted below to incorrectly set and illuminate the MIL in the ECM.
Some technicians may find one or more of the following DTCs set in the ECM:
• P0690: Engine Controls Ignition Relay Feedback Circuit High Voltage
• P16B3: Engine Controls Ignition Relay Feedback Circuit 2 High Voltage
Some technicians may also find P2420 (Evaporative Emission System Vacuum Leak
Pump module switching valve shorted to battery) set in History in the ECM.

Cause

This condition may be caused by a short to power in the wiring or connectors to the
Evaporative Emission System Vacuum Leak Pump.

Correction

Check wiring and connectors to the Evaporative Emission System Vacuum Leak Pump
for continuity and shorts and repair/replace wiring issues.
⇒ If no wiring issues are found, then replace the Evaporative Emission System Vacuum Leak Detection Pump.

Important: Service agents must comply with all International, Federal, State, Provincial, and/or Local laws
applicable to the activities it performs under this bulletin, including but not limited to handling, deploying,
preparing, classifying, packaging, marking, labeling, and shipping dangerous goods. In the event of a
conflict between the procedures set forth in this bulletin and the laws that apply to your dealership, you
must follow those applicable laws.

Service Procedure
Refer to Wire to Wire Repair in SI.

Copyright 2025 General Motors. All Rights Reserved.

Page 2

February, 2025

Bulletin No.: 25-NA-025

Warranty Information
For vehicles repaired under warranty, use:
Labor Operation

Description

5430902

Wire-to-Wire Repair

4027810

Evaporative Emission System Vacuum Leak Detection Pump
Replacement

Version

1

Modified

Released February 18, 2025

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job
properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.

Labor Time
Use the Published Labor
Operations Time

WE SUPPORT VOLUNTARY
TECHNICIAN
CERTIFICATION