2026 Mack Pioneer Pr (4) problems, complaints & recalls
Safety recalls (9)
Structure:body:bumpers:active Shutters/Grill 2026-10-01 · campaign 26V631000 · 3,096 vehicles
Defect: Mack Trucks, Inc. (Mack) is recalling certain 2026-2027 Anthem AN (4) and 2025-2027 Pioneer PR (4) vehicles. The intake and grille bezels may detach from the vehicle.
Risk: A detached bezel can become a road hazard for other vehicles, increasing the risk of a crash.
Fix: Dealers will inspect, replace the intake and grille bezels, and install cable ties as necessary, free of charge. Owner notification letters are expected to be mailed November 30, 2026. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0501. Vehicle Identification Numbers (VINs) involved in this recall will become searchable on NHTSA.gov on October 8, 2026.
Service Brakes, Electric:software/Programming 2026-09-28 · campaign 26V620000 · 850 vehicles
Defect: Mack Trucks, Inc. (Mack) is recalling certain 2026-2027 Anthem AN (4) and Pioneer PR (4) vehicles equipped with a tanker application package. Inaccurate axle load calculations may cause reduced braking performance while transporting smoothbore tanker trailers.
Risk: Reduced braking performance can require a greater distance to stop, increasing the risk of a crash.
Fix: Dealers will install new software to disable the dynamic trailer braking calculations, free of charge. Owner notification letters are expected to be mailed November 27, 2026. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0500. Vehicle Identification Numbers (VINs) involved in this recall will become searchable on NHTSA.gov on October 5, 2026.
Wheels:lugs/Nuts/Bolts/Studs 2026-05-28 · campaign 26V351000 · 644 vehicles ⚠ DO NOT DRIVE
Defect: Mack Trucks, Inc. (Mack) is recalling certain 2026 Anthem (AN), 2026-2027 Pioneer PR (4), Pinnacle (PI/PN), Granite (GR), and 2027 Anthem AN (4) vehicles. The wheel lug nuts may loosen and allow the wheel to detach.
Risk: Wheel detachment can cause a loss of vehicle control or create a road hazard, increasing the risk of a crash or injury.
Fix: Owners are advised not to drive their vehicles until the repair has been performed. Dealers will inspect the wheel and hub mating surfaces, remove any masking material, and replace any worn components if necessary, free of charge. Owner notification letters were mailed June 22, 2026. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0495. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov on May 31, 2026.
Service Brakes, Air:antilock:control Unit/Module 2026-04-23 · campaign 26V261000 · 2,772 vehicles
Defect: Mack Trucks, Inc. (Mack) is recalling certain 2025-2027 Pioneer (4) and 2026-2027 Anthem (4) vehicles. The rear brake modulators may have unprotected electrical connectors that can short circuit and lead to a loss of the anti-lock brake system (ABS) and electronic stability control (ESC).
Risk: A loss of anti-lock brakes and electronic stability control increases the risk of a crash or injury.
Fix: Dealers will inspect the rear brake modulator electrical connectors, install a protective cover, and replace the rear brake modulators, as necessary, free of charge. Owner notification letters were mailed June 8, 2026. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0494. Vehicle Identification Numbers (VINs) involved in this recall will be searchable on NHTSA.gov beginning April 30, 2026.
Exterior Lighting:turn Signal 2026-04-01 · campaign 26V207000 · 86 vehicles
Defect: Mack Trucks, Inc. (Mack) is recalling certain 2025-2027 Pioneer (4) and 2027 Anthem (4) trailers. The trailer turn signals may not function properly. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 108, "Lamps, Reflective Devices, and Associated Equipment."
Risk: Turn signals that do not function properly may fail to indicate the driver's intention to change vehicle direction, increasing the risk of a crash.
Fix: Dealers will update the turn signal indicator software, free of charge. Owner notification letters were mailed May 7, 2026. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0493. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov April 1, 2026.
Equipment:mechanical 2025-11-20 · campaign 25V801000 · 46 vehicles
Defect: Mack Trucks, Inc. (Mack) is recalling certain 2025-2026 Pioneer vehicles. The load lock clamps, located on the back of the cab, may loosen and cause the load lock bars to become unsecured.
Risk: A loose or unsecured load lock bar can result in a loss of cargo, creating a road hazard and increasing the risk of a crash.
Fix: Dealers will replace the load lock clamps, free of charge. Owner notification letters were mailed December 18, 2026. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0489. Vehicle Identification Numbers (VINs) involved in this recall will be searchable on NHTSA.gov beginning November 27, 2025.
Exterior Lighting:lighting Control Module:software 2025-11-20 · campaign 25V803000 · 247 vehicles
Defect: Mack Trucks, Inc. (Mack) is recalling certain 2026 Anthem (4) and 2025-2026 Pioneer vehicles. The automatic high beams (AHB) may not switch to low beam headlights as intended. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 108, "Lamps, Reflective Devices, and Associated Equipment."
Risk: High beam headlights that do not switch to low beam as intended can reduce visibility for oncoming traffic, increasing the risk of a crash.
Fix: As an interim action, Mack will update the vehicle software through an over-the-air (OTA) update to disable the AHB feature, free of charge. Owner letters were mailed May 29, 2026. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0488. Vehicle Identification Numbers (VINs) involved in this recall will be searchable on NHTSA.gov beginning November 27, 2025.
Exterior Lighting:lighting Control Module 2025-09-18 · campaign 25V622000 · 156 vehicles
Defect: Mack Trucks, Inc. (Mack) is recalling certain 2025-2026 Pioneer vehicles. When towing a trailer, the trailer lights may fail to illuminate due to an improperly manufactured body control module.
Risk: Trailer tail lights and turn signals that do not illuminate as intended can reduce visibility to other drivers, increasing the risk of a crash.
Fix: Dealers will replace the trailer body input/output module, free of charge. Owner letters were mailed November 19, 2025. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0484.Vehicle Identification Numbers (VINs) involved in this recall will be searchable on NHTSA.gov beginning September 25, 2025.
Steering 2025-08-11 · campaign 25V521000 · 32 vehicles
Defect: Mack Trucks, Inc. (Mack) is recalling certain 2025 Anthem and 2025-2026 Pioneer vehicles. The dynamic steering and oversteer guidance feature may malfunction and cause a loss of steering control.
Risk: A loss of steering control increases the risk of a crash.
Fix: The oversteer guidance feature will be disabled through an over-the-air (OTA) update or by a dealer, free of charge. Owner notification letters were mailed August 21, 2025. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0483.
Service bulletins (100)
Technical service bulletins are repair instructions manufacturers send dealers for known issues. Unlike recalls, the fix is not automatically free — but naming the bulletin at the service desk can save diagnosis time and support goodwill repairs.
Electrical System 2026-09-27 · TSB M-373-003 202609 · Service Bulletin/Repair Instructions
power cable alternator replacement
Electrical System 2026-09-24 · CBR 2590-3 202609 · Service Bulletin/Repair Instructions
instrument cluster going dark
Electrical System 2026-09-17 · CBR 2483-6 202609 · Service Bulletin/Repair Instructions
diagnostic instructions for can network communication issues.
Electrical System 2026-09-08 · CBR 2496-18 202609 · Service Bulletin/Repair Instructions
the purpose of this cbr is outline the interim software solution for pr(4) and an(4).
Electrical System 2026-09-01 · TSB M-371-005A 202609 · Service Bulletin/Repair Instructions
jumper harness repair for version 4 mack trucks
Engine 2026-08-26 · TSB M257005 202608 · Service Bulletin/Repair Instructions
loose ccv mounting bolts and oil leak at ccv due to cracking of the housing. mounting hardware found to be under-torqued after the vehicle was delivered.
Showing the 6 most recent of 100 bulletins. Search all of them free at nhtsa.gov.
What owners report
No detailed complaint narratives on file.
Excerpts of consumer complaints filed with NHTSA, lightly truncated. They are owner statements, not verified findings.