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Service bulletin K55905221

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id10141396
Published by NHTSA2018-06-18
Manufacturer's numberK55905221
Manufacturer's date2018-04-19
NHTSA componentENGINE

NHTSA's summary

Mack Chassis - Diagnostic Trouble Code ( DTC ) P0420 Illuminating The Malfunction Indicator Lamp (MIL) - US17+OBD16 And US17+OBD18 (GHG17) Emissions (Common Rail Fuel System) - Commonly Model Years 2018 And 2019

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Engine

Trouble codes named

P0420

Vehicles listed
MACK ANTHEM (AN)2018, 2019 (the catalog's model; the bulletin names a series or trim of it)
MACK CHU2018
MACK CXU2018
MACK GU2018
MACK LR2018, 2019
MACK MRU2018

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Other bulletins for the same vehicles and component
M0304 EC0033 2026062026-06-29. Emissions. Mack Trucks has determined that certain vehicles equipped with a model year (“MY”) 2017-2018 MP8 Turbo Compound (TC) engine may not meet California and Federal Regulations (CARB). This Recall is for updated software that will reduce the amount of time necessary for the system to operate in a cold engine warm-up strategy and provide health monitoring of the Selective Catalyst Reduction (SCR).
M0039 0320262026-04-02. Emissions. Emissions - EC0039 MST21 Failure to Detect P20EE - AN, CHU.
M0302 0220262026-03-03. Emissions. Emissions - Mack Trucks has determined that certain vehicles equipped with a model year (“MY”) 2017-2018 MP7 engine may not meet California and Federal Regulations (CARB).
CBR 820-9 2026012026-02-03. Service bulletin. CBR - Mack Chassis - Engine Brake Only Works With The Brake Pedal, No Function During Cruise. US07 And Newer Emissions, Model Year 2008 And Newer.
CBR 2107-22 2026012026-02-02. Service bulletin. CBR - Mack DEF Level (UQLS) Sensor Troubleshooting Guide - US17+OBD16 Emissions to US22+OBD2023 (DOES NOT APPLY TO AN(4) and PR(4)).
CBR 199 2025122026-01-05. Service bulletin. Vehicles affected by this issue will show coolant runoff on the front rights side of the engine.
CBR 2171-11 2025112025-12-03. Service bulletin. CBR - Mack Temperature Sensor Troubleshooting Guide
CBR 199-6 2025112025-12-03. Service bulletin. CBR - 13 Liter Engines ONLY - Engine Coolant Pump Housing Leak; Coolant Found Around The Oil Cooler Duct Cover Or In Between The Coolant Pump Housing And Oil Cooler Housing.
CBR 2107-21 2025052025-06-02. Service bulletin. Mack DEF Level (UQLS) Sensor Troubleshooting Guide - US17+OBD16 Emissions and Newer
CBR 170-8 2025052025-06-02. Service bulletin. Inactive Code P25AE00 Being Generated After A Hard Pull And A Momentary Drop In Engine Oil Pressure (Low Oil Pressure) (Possible Related Codes - SPN4811 , SPN 100 , PID 100)