The worst 2026 Mack Pioneer PR (4) problems
Ranked by number of owner complaints. Mileage and cost come from what owners wrote.
Problems by type
Tap a problem to see which part fails, at what mileage and in which other years.
Recalls 9
Structure: body: bumpers: active shutters/grill
- What is wrong
- 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.
- Remedy
- 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 on October 8, 2026.
Recall number 26V631000 · Recall details
Service brakes, electric: software/programming
- What is wrong
- 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.
- Remedy
- Dealers will install new software to disable the dynamic trailer braking calculations, free of charge. Owner notification letters were mailed October 29, 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 on October 5, 2026.
Recall number 26V620000 · Recall details
Wheels: lugs/nuts/bolts/studs
- What is wrong
- 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.
- Remedy
- 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 on May 31, 2026.
Recall number 26V351000 · Recall details
Service brakes, air: antilock: control unit/module
- What is wrong
- 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.
- Remedy
- 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 beginning April 30, 2026.
Recall number 26V261000 · Recall details
Exterior lighting: turn signal
- What is wrong
- 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.
- Remedy
- 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 April 1, 2026.
Recall number 26V207000 · Recall details
Equipment: mechanical
- What is wrong
- 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.
- Remedy
- 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 beginning November 27, 2025.
Recall number 25V801000 · Recall details
Exterior lighting: lighting control module: software
- What is wrong
- 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.
- Remedy
- 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 beginning November 27, 2025.
Recall number 25V803000 · Recall details
Exterior lighting: lighting control module
- What is wrong
- 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.
- Remedy
- 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 beginning September 25, 2025.
Recall number 25V622000 · Recall details
Steering
- What is wrong
- 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.
- Remedy
- 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.
Recall number 25V521000 · Recall details
Technical service bulletins for the 2026 Mack Pioneer PR (4) 107
Bulletins tell dealers how to fix known problems. A warranty extension means the manufacturer pays for that repair for longer.
- This document provides guidance for addressing the APM DTC C10129B fault, "High/Excessive Flow"
- The purpose of this CBR is to address issues of Automatic High Beam functionality
- This document provides guidance for No-Crank/No-Start or Blank Instrument Cluster following shop...
- The purpose of this CBR is to provide steps on how to utilize the injector widget (within workshop...
- All Mack vehicles built with USA24, and forward emissions may experience damage to the diesel exhaust...
- Trucks equipped with large sleeper cab variants may experience vibration at speeds 62
- Vehicles had TPMS sensors mounted incorrectly causing damage to the bead when the tire is mounted
- Power Cable Alternator Replacement
- Instrument Cluster Going Dark
- Diagnostic instructions for CAN network communication issues.
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Questions about the 2026 Mack Pioneer PR (4)
Is the 2026 Mack Pioneer PR (4) reliable?
Owners have filed 0 complaints about the 2026 Mack Pioneer PR (4).
What is the most common problem with the 2026 Mack Pioneer PR (4)?
There are not enough complaints to tell.
How many recalls does the 2026 Mack Pioneer PR (4) have?
9 recalls, covering structure, service brakes, electric and wheels.
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