2013 Mack MRU Problems, Complaints & Recalls

Problem: Mack Trucks, Inc. (Mack) is recalling certain 2010-2018 MRU and 2019-2025 Terrapro towing vehicles. The vehicles are missing the anti-lock brake (ABS) warning light and circuitry that controls the anti-lock brake function for an attached trailer. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 121, "Air Brake Systems."

Risk: Driving without a functioning anti-lock brake system may result in the trailer not braking as intended, increasing the risk of a crash.

Fix: Dealers will add an ABS warning light and circuitry, free of charge. Owner notification letters were mailed April 28, 2025. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0474.

Problem: Mack Trucks, Inc. (Mack) is recalling certain model year 2011-2016 Mack MRU and LEU trucks manufactured June 25, 2010, to April 30, 2015, and 2015-2016 LR6 trucks manufactured from December 18, 2014 through March 6, 2015. Excessive engine crankcase pressures may cause the 90-degree elbow of the vent tube assembly to detach from the crankcase ventilation breather, possibly allowing engine oil to come into contact with hot surfaces.

Risk: If engine oil comes into contact with a hot surface, there could be an increased risk of a fire.

Fix: Cummins will notify owners on behalf of Mack, and Cummins service centers will administer the repairs which include securing the ends of the 90-degree elbow and reprogramming the electronic control module (ECM) with software that can adjust the engine output under misfire conditions to limit crankcase pressures. These repairs will be performed free of charge. The recall began on June 12, 2015. Owners may contact Mack customer service at 1-800-528-6586 or Cummins Inc. at 1-800-343-7357. Mack's number for this recall is SC0391.

Problem: Mack Trucks Inc. (Mack) is recalling certain model year 2010-2014 CHU, CXU, and MRU, 2007 CT and CV, 2008-2014 GU, and 2011-2014 LEU, and TD trucks manufactured February 28, 2006, through November 8, 2013, and equipped Hamsar Electronic Flasher. The hazard warning lights may fail.

Risk: A failure of the hazard warning lights could reduce the trucks visibility, increasing the risk of a crash.

Fix: Mack will notify owners, and dealers will replace the electronic flasher unit, free of charge. The recall will begin by mid-June 2014. Interim letters went out to owners on June 23, 2014. The recall began on July 25, 2014. Owners may contact Mack customer service at 1-866-298-6586. Mack's number for this recall is SC0379.

Problem: Mack Trucks Inc. (Mack) is recalling certain model year 2014-2015 CXU, 2010-2015 LEU, and 2011-2015 MRU vehicles manufactured with certain Cummins Westport Model ISL G and ISX12 G engines. Condensation in the intake manifold may freeze during cold weather conditions and interfere with the proper operation of the intake manifold pressure sensor.

Risk: The improper operation of the sensor could induce elevated exhaust temperatures or flames from the exhaust pipe, increasing the risk of a vehicle fire or burn injury to a person near the exhaust pipe.

Fix: Cummins and Cummins Westport will notify owners, and authorized Cummins service facilities will upload a new ECM calibration, free of charge. The recall began on March 12, 2014. Customers may contact Mack at 1-336-393-2000 or Cummins Inc. at 1-800-343-7357. Mack's number for this recall is SC0377.

Problem: Mack Trucks is recalling certain model year 2013-2014 CHU, CXU, GU, LEU, and MRU vehicles manufactured with pro-torque axle spindle nuts from August 28, 2012, through August 16, 2013. The pro-torque nut may not have been installed correctly, which may result in a loosening of the nut.

Risk: If the nut comes loose, the hub assembly may separate from the vehicle, increasing the risk of a crash.

Fix: Mack Trucks will notify owners, and dealers will inspect and repair the vehicles, as necessary, free of charge. The recall began on November 12, 2013. Mack's recall number is SC0371. Owners may contact Mack Trucks at 1-336-393-2000.

Problem: Mack Trucks, Inc. is recalling certain model year 2013-2014 CHU, CXU, GU, MRU, and LEU trucks manufactured July 16, 2012, through march 18, 2013 and equipped with drum brakes. The clevis pin for the brake slack adjuster may be missing a cotter pin. If the cotter pin is not installed, the clevis pin may loosen and fall out causing a loss of brake function on the affected wheel.

Risk: A loss of brake function at one wheel will lead to increased stopping distances and pulling to the left or right when braking, which may increase the risk of a crash.

Fix: Mack Trucks, Inc. will notify owners, and dealers will inspect the brake slack adjusters and install the brake hardware, as necessary, free of charge. An interim was mailed to owners on June 20, 2013. A second notice was mailed to owners on September 30, 2013. Owners may contact Mack Trucks at 1-800-528-6586. Mack Trucks' recall campaign number is SC0370.