- The problem
- Mack Trucks, Inc. (Mack) is recalling certain 2023 MD6/7 trucks. The engine control module (ECM) may experience an internal short-circuit, which can result in an unexpected engine shut down.
- The risk
- An unexpected engine shut down can increase the risk of a crash.
- The fix
- Cummins will replace the ECM, free of charge. Owner notification letters were mailed on September 27, 2022. Owners may contact Mack's customer service at 1-800-866-1177. Mack's number for this recall is SC0438.
Engine & cooling
2023 Mack MD Engine problems
Owners have filed 1 complaint about the 2023 Mack MD's engine & cooling with NHTSA - 100% of all its complaints, most recently on June 17, 2026. Stalling, loss of power, oil consumption, overheating, head gaskets, timing chains and engine failure.
- Complaints
- 1
- Recalls
- 1
- Crashes
- 0
- Fires
- 0
- Injuries
- 0
- Deaths
- 0
Engine recalls for the 2023 Mack MD
Engine complaints
COMPONENTS THAT FAILED: Multiple systems failed in a connected chain. (1) The DPF aftertreatment differential pressure sensor - a CONFIRMED manufacturing defect per Cummins recall T7186/T7187 (Jan 2026). (2) The Allison automatic transmission - catastrophic internal failure: torque converter destroyed, flexplate warped and cracked, metal fragments throughout. (3) The transmission control unit wiring (circuits 143/123) reversed at the factory. The DEF sensor in the same aftertreatment system also failed back in Dec...
Read the full complaint
2023, 14 months before the DPF symptoms - proving a system-wide defect. All failed components and repair invoices are available for inspection upon request. SAFETY RISK: After the dealer declared repairs complete, the truck was driven under 10 miles when the engine entered SEVERE DERATE (limp) mode WITHOUT WARNING, with four alerts firing at once including aftertreatment and transmission failures. Sudden, drastic power loss on a heavy commercial truck in live traffic is extremely dangerous - it can leave the vehicle unable to maintain highway speed, risking a collision with surrounding vehicles. The dealer released the truck in this hazardous state with no warning. CONFIRMED BY MULTIPLE SHOPS: Yes. The problem was reproduced and confirmed repeatedly - by the authorized dealer, by an independent transmission shop, and at final repair. The fault returned within 30 minutes on one visit and within 10 miles on another. INSPECTED BY: The authorized dealer and an independent service center inspected the vehicle and failed components. Documentation is available. WARNING SIGNS: Yes. Warning lamps appeared from the very first visit in Feb 2025 - transmission code P071A and high soot codes 1981/1922. They persisted for NINE MONTHS without proper repair, until the transmission catastrophically failed in Nov 2025. The vehicle was out of service over 45 days.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) complaints and recalls, checked . Complaints are owners' own reports and are not verified. How we use the data