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Decoding Engine DTC Faults for your CMV

March 12, 2024

Engine DTC codes are your vehicle's way of sending an error message. Understanding what these codes mean is essential for keeping your vehicles running smoothly.

In this article

If you manage a commercial fleet, you've probably encountered those mysterious Engine DTC (Diagnostic Trouble Code) lights on your vehicles' dashboards. Understanding what these codes mean and how they can affect your fleet is essential for keeping your vehicles running smoothly.

Engine DTC codes are like your vehicle's way of sending an SOS message. When something isn't quite right under the hood, the vehicle's onboard computer system generates these codes to pinpoint the issue. These codes can represent various problems, from minor glitches to serious malfunctions.

How Do DTC Codes Affect Commercial Fleets?

Engine DTC codes can have significant consequences for commercial fleets. Here's how they can affect your operations:

Vehicle Downtime

When a DTC code is triggered, the vehicle's computer system often puts the vehicle in a "limp mode" or disables certain functions to prevent further damage. This means the vehicle might not operate at full capacity or may not be drivable at all until the issue is resolved. Vehicle downtime can disrupt your schedule and impact your bottom line.

Maintenance Costs

Addressing DTC codes typically involves diagnosing and repairing the underlying issue. Depending on the severity of the problem, this can lead to significant maintenance costs. Preventive maintenance and regular inspections can help catch issues before they trigger DTC codes, potentially reducing repair expenses.

Fuel Efficiency

Some DTC codes can relate to fuel system problems or inefficient engine performance. Ignoring these codes can lead to reduced fuel efficiency, increasing your fuel costs over time. Addressing them promptly can help maintain optimal fuel economy.

Vehicle Safety

Certain DTC codes can indicate safety-related issues, such as brake system problems or airbag malfunctions. Ignoring these codes can compromise the safety of your drivers and others on the road, potentially leading to accidents and liabilities.

Regulatory Compliance

Commercial vehicles must adhere to strict safety and emissions regulations. Ignoring or neglecting DTC codes that relate to these areas can result in compliance violations and fines.

If you want to learn more about maintaining your CSA score, read our post about CSA Scores - Why and how to improve your CSA Score

How to handle DTC codes

Here's a best practice guide on how to effectively address DTC codes in your commercial fleet

Immediate Response

As soon as a DTC code is registered, it's crucial to take immediate action. Ignoring or delaying a response can lead to more significant issues and potentially costly repairs down the road.

  • Notify the Driver: If the DTC code is reported by a driver, ensure they are aware of it and understand the importance of reporting such issues promptly.
  • Use Diagnostic Tools: Invest in high-quality diagnostic tools and software that can accurately read and interpret DTC codes. These tools provide valuable information about the specific issue affecting the vehicle.
  • Retrieve Code Details: Access the code's detailed information, including the code itself, its description, and any additional data such as freeze-frame data or pending codes. This information helps in diagnosing the problem.
Some diagnostic tools, like Switchboard, let you understand DTC codes as they occur

Determine Severity & Plan Repairs

Not all DTC codes represent critical issues. Some may be minor or intermittent. Evaluate the severity of the problem to prioritize repairs accordingly.

  • Identify the Problem: Use the DTC code as a starting point to identify the underlying problem. Diagnose the issue thoroughly to avoid misdiagnosis and unnecessary repairs.
  • Estimate Repair Costs: Estimate the cost of repairs and evaluate whether it makes financial sense to address the issue immediately or schedule it as part of routine maintenance.
  • Qualified Technicians: Ensure that repairs are carried out by qualified technicians who have experience with the specific vehicle make and model. They should also be familiar with the diagnostic information provided by the DTC code.

Document and Track

Maintain detailed records of all DTC codes, including the date, code description, repairs performed, parts replaced, and associated costs. This information helps track vehicle maintenance and identifies recurring issues.

  • Inform Drivers: Keep your drivers informed about the status of repairs and any additional steps they need to take to ensure the vehicle's safe operation.
  • Driver Training: Consider providing drivers with basic training on recognizing common DTC code symptoms and how to respond appropriately.

Preventive Maintenance

Implement a proactive preventive maintenance schedule that includes regular checks and inspections to catch and address issues before they trigger DTC codes.

  • Analyze DTC Data: Periodically review DTC data to identify trends or recurring issues across your fleet. This can guide preventive maintenance efforts and highlight areas for improvement.
  • Learn from DTCs: Use DTC codes as learning opportunities to improve fleet maintenance practices continually. Identify root causes of issues and implement preventive measures.

Understanding engine DTC codes and their impact on your commercial fleet is crucial for maintaining efficiency, safety, and compliance. By proactively addressing these codes and implementing preventive maintenance practices, you can keep your fleet running smoothly and minimize disruptions to your operations.

Switchboard provides fleet management technology that informs you about engine DTC codes in real-time, allowing you to assess and manage your vehicles maintenance proactively. Learn more here.

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