MACK ECM | V-MAC 12MS51M2 Repair

Original price was: $799.00.Current price is: $699.00.

Mack 12MS51M2 | V-MAC ECM Repair Service

Your ECM will be returned fully reconditioned, tested, and ready to be installed back to the exact vehicle it came off, saving you the time & expense of having a new ECM programmed to your machine. We first diagnose the unit. If the item cannot be repaired or no issues are found, the cost is $200 plus return shipping.

In this case, we will process a partial refund for the difference.


Mack ECM. V-MAC 12MS51M2. Repair Service. Your ECM will be returned fully reconditioned, tested, and ready to be installed back to the exact vehicle it came off, saving you the time & expense of having a new ECM programmed to your machine.

P/N: 12MS51M2

We first diagnose the unit; if it’s not repairable or no problems are found, it costs $200.

In this case, we will process a partial refund for the difference.

Mack ECM 12MS51M2

The ECM (Engine Control Module) is crucial to a diesel engine’s operation. It acts as the brain of the engine, monitoring and controlling various parameters to ensure optimal performance, fuel efficiency, and emission levels. The ECM plays a significant role in fuel injection timing, turbocharger boost pressure, idle speed control, and troubleshooting diagnostic codes.

The ECM Mack 12MS51M2, also known as the Engine Control Module for Mack trucks, is a crucial component in the vehicle’s electronic control system. This ECM model is designed specifically for Mack trucks to manage and optimize engine performance, fuel efficiency, emissions, and overall vehicle operation.

The 12MS51M2 ECM is equipped with advanced microprocessors and software algorithms that continuously monitor various parameters such as engine speed, temperature, pressure, and exhaust gas composition. It processes this data in real-time to make adjustments to fuel injection timing, air-fuel mixture, turbocharger boost levels, and other engine functions to ensure optimal performance and efficiency.

In addition to performance optimization, the ECM also plays a key role in diagnosing and troubleshooting engine issues by storing fault codes and providing valuable diagnostic information to mechanics and service technicians. This helps in quickly identifying and resolving any potential problems, minimizing downtime and maintenance costs for Mack truck owners.

What is the 12MS51M2 module?

Description: The Mack ecm 12MS51M2 module is a specialized ECM in specific Mack truck models. It is designed to control and optimize the performance of Mack diesel engines in terms of power output, fuel efficiency, and emissions compliance.

  1. Functionality: The 12MS51M2 module is primarily responsible for managing fuel injection timing, air-to-fuel ratio control, engine speed regulation, and emission control systems. It continuously monitors various engine parameters using input signals from sensors throughout the engine.
  2. Troubleshooting: If the 12MS51M2 module has issues, proper diagnostic procedures must be followed to identify the root cause accurately. This may involve specialized diagnostic tools like Mack’s dealer-level software or third-party diagnostic systems compatible with these engines.
  3. Repair and Maintenance: When repairing or maintaining the 12MS51M2 module, following Mack’s recommended service procedures and guidelines is crucial. This may include inspecting and cleaning electrical connections, ensuring proper grounding, and replacing faulty components if necessary. It is generally recommended that repairs be done by experienced technicians familiar with ECM systems.
  4. Software Updates: Like any electronic module, the 12MS51M2 module may require periodic software updates to address known issues, improve performance, or comply with new regulations. Mack dealerships or authorized service centers can assist with updating the ECM software using their specialized tools and database.
  5. Availability of Parts: If any component of the 12MS51M2 module needs replacement, it is advisable to contact authorized parts dealers or service centers. They can help source genuine Mack parts to ensure proper functioning and compatibility.

Common Problems

  • Blowing fuses
  • No communication
  • Engine shutting down
  • Fault codes in the unit
  • Intermittent faults
  • Oil intrusion
  • Water damaged
  • Injector driver faults


You only send your unit to us; we will diagnose the faults and return the fixed unit.

Why trust us

Our engineering team has over 15 years of experience, more than 10K repaired ECMs, and the latest simulation technology. We are always happy to assist you with any technical assistance we can. Feel free to contact us to discuss the faults you are experiencing before sending in your parts.

ECM Engineering USA / ECM Repair USA

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4 Steps

4 Steps

Additional information

Weight160 oz
Dimensions11 × 14 × 7 in