Failure Codes in Maintenance: What They Are, Why They Matter, and Best Practices

Most maintenance managers have faced the dreaded mystery failure. A machine went down, the team fixed it under pressure, but no one documented the root cause clearly.

Without a standardized way to capture why assets fail, you’re flying blind. Patterns are missed, repeat failures creep up, and precious data slips through our fingers. Technicians might scribble “repaired motor” in a work order, but that tells you nothing about the underlying issue – was it a power surge? A bearing failure due to misalignment? Over time, this lack of insight costs dearly: you replace the same parts over and over, unable to address the real cause.

It’s frustrating for a maintenance personnel to know there’s a wealth of failure information in your operation, yet it remains untapped. You suspect that 5 similar breakdowns last quarter likely had a common cause, but you have no easy way to prove it. Meanwhile, upper management is asking why downtime isn’t going down – you could explain the chronic issues if only you had the data organized.

If you use failure codes – a simple, structured way to turn maintenance experiences into actionable data – you have solutions to all these issues. Using failure codes in your maintenance operations creates a feedback loop: every fix teaches you something. Let’s discuss what failure codes are, why failure codes are used in maintenance management, and what are the best practices for implementing an effective failure coding system.

What is a “Failure Code” in Maintenance?

A failure code is a short alphanumeric code, tag, or descriptor used to record the reason for component or asset failure. In a maintenance context – especially within a maintenance management software or enterprise asset management system – failure codes help provide a standardized language for failure causes. Instead of writing a long narrative each time something breaks, the technician selects predefined codes that categorize the problem.

For instance, a failure code might indicate “Bearing failure due to fatigue” or “Motor failure – electrical short”, encapsulating the essence of what went wrong in a few characters. You thus have failure trends at your disposal and it becomes easy to track and address failures.

Failure codes are thus like a diagnosis a physician writes in a medical record, but for machines. Just like a doctor uses standardized codes to record illnesses (for consistency and analysis), maintenance teams use failure codes to consistently record equipment ills in the maintenance records. A simple code might be something like “ELEC-Short” for an electrical short-circuit, or “MECH-Wear” for a mechanical failure due to wear and tear. So, when you apply failure codes, they get attached to work orders or incident reports and build a historical database of why things fail.

In practice, failure codes are often structured in a hierarchy or in multiple fields:

• A Problem code: What was observed to be wrong, e.g. pump won’t start or high vibration.
  
• A Cause code: The identified root cause, e.g. coupling misaligned or bearing fatigue.
  
• An Action code: The remedy taken, e.g. replaced bearing or realigned coupling.

This Problem-Cause-Action framework is commonly used in maintenance strategies. To illustrate, let’s say a motor in an HVAC system stopped working. Without failure codes, a tech might write “motor fixed” in the notes. With failure codes, they would select something like:

• Problem: Motor stopped (Code MSTOP) – indicating the functional failure.
  
• Cause: Overheated – winding insulation failure (Code OVERHT) – indicating the root cause (maybe poor ventilation or overload led to overheating).
  
• Action: Replaced motor (Code RPLC) – indicating what was done to fix it.

Now, when this data is saved, anyone later can query all “OVERHT” failures or see how often motors are replaced vs. repaired. The key is that by using consistent codes, you turn anecdotal fixes into structured data.

What is the Importance of Failure Codes in Maintenance?

Failure codes may seem bureaucratic at first, but they provide significant value for sustaining maintenance efficiency. They bring a level of discipline and analysis that is hard to achieve with free-form text descriptions alone and convert maintenance activities into intelligence. Following are the reasons that highlight their importance in detail:

• Identify Patterns and Recurring Problems: Humans are notoriously bad at recalling precise histories, especially over hundreds of incidents. Failure codes enable the CMMS to do the heavy lifting. For example, you can pull a report of all failures in the past year and see that a particular failure code – say, “Bearing fatigue” – appears 15 times on a specific pump model. That’s a red flag. Perhaps it indicates a design issue or a misapplication. You might not have noticed this pattern without coded data.
  
• Faster Troubleshooting: When a machine fails, technicians mostly reference past work orders on that asset to see what happened before. If those work orders have clear failure codes, the troubleshooting is much quicker. This way failure codes allow maintenance teams to leverage past experience efficiently and also improve asset management efficiency.
  
• Preventive Maintenance Optimization: Understanding the reasons behind equipment failures is essential for preventing them. If data indicates that most failures of a specific piece of equipment are related to lubrication issues, you can enhance your preventive maintenance for lubrication or switch to a higher-quality lubricant. Many organizations utilize failure data, often aligned with standards such as Reliability-Centered Maintenance strategies (RCM), to improve their preventive maintenance program. This approach is fundamental to reliability engineering: identifying failure modes and mitigating them.
  
• Justify Capital and Reliability Investments: Maintenance managers need to make the case for replacing an asset or investing in improvements. Hard data from failure codes is compelling. You can go to finance and say, “Look, this machine failed 12 times this year due to the same cause. It cost us X in parts and downtime. If we invest in a new machine or a redesign, we eliminate those 12 failures (supported by data).” It moves the conversation from opinion to evidence.
  
• Compliance and Reporting: In certain industries, such as aviation, healthcare, and oil and gas, regulatory standards require failure tracking and their causes. For example, ISO 14224 is a standard for the petroleum industry that outlines how to collect and exchange reliability and maintenance data, including information on failure causes. Having an effective failure coding system makes it significantly easier to comply with these standards in maintenance. With a good system in place, you can generate failure reports on rates and causes of failure for audits or regulatory submissions without any last-minute scrambling.
  
• Improve Communication and Knowledge Transfer: Maintenance teams typically include veterans with decades of know-how and entrants who are still learning. Failure codes create a common language that both can use. Over time, this practice trains people to think about causes, not just symptoms. It also means that if a senior technician retires, his years of troubleshooting knowledge aren’t lost; they’re embedded in the historical failure data. New hires can review failure code histories to get up to speed on what typically goes wrong in the plant.

What are the Best Practices for Implementing Failure Codes?

Introducing failure codes into your maintenance process requires planning and ongoing management. Following are the failure codes best practices gleaned from both industry standards and successful implementations:

1. Develop a Standardized Coding Structure:Before rolling out failure codes, design the structure. A common mistake is to either use too few codes (overly general) or too many (overly specific). If you want a balanced, hierarchical structure, follow the three-tier Problem-Cause-Action format discussed above, because it aligns with how troubleshooting works.
2. Consult industry references or standards for guidance: As mentioned, ISO 14224 provides a taxonomy for failure data – including failure modes and causes – which can serve as a solid foundation. Additionally, many CMMS vendors or communities have sample code lists that you can adapt. The key is ensuring the codes cover your common failure scenarios without being redundant. Aim to cover the “vital few” causes that represent the majority of your issues, and have some generic options (like “Other – specify”) for rare cases.
   
3. Keep the Code Library Manageable: It’s tempting to create an exhaustive list of codes for every conceivable failure. Avoid that trap. An overly complex number of codes will overwhelm users and will either pick the wrong codes or give up. A good practice is to keep codes to a minimal yet sufficient set. Perhaps 10-15 top-level problem codes, each with maybe 5-10 cause codes under them, etc., depending on your operation’s complexity.
   
4. Use Clear, Unambiguous Names: Each code should be easily understood by your team. Avoid overly cryptic abbreviations. It’s fine if the code itself is a short acronym, but the description should be plain language (e.g., code “OVHT” with description “Overheated”, or code “MISALG” for “Misalignment”). Make sure different codes aren’t so similar that users get confused.
   
5. Train and Engage the Team: Roll out failure codes as a part of maintenance training. Explain to technicians why you are doing this and how it will help them in the long run. Provide them examples of how to select codes. Possibly create a quick reference chart or even integrate hints into the CMMS. Encourage technicians to be part of the process: if they feel a code doesn’t exist for what they found, have a process to capture that feedback so you can consider adding it.
   
6. Enforce Usage Through Process and CMMS Settings: People might forget or skip entering failure codes unless the process enforces it. If possible, configure your CMMS to make certain fields (like failure cause) mandatory before closing a work order. Supervisors should also reinforce this: review completed work orders, and if any come through without codes or with obvious mids-codings, follow up. Consider it similar to how safety incident reporting is handled: thorough and standardized.
   
7. Consult Existing Standards or Libraries: You don’t have to invent everything from scratch. As noted, ISO 14224 is great if you’re in applicable industries. SAE JA1011 (for reliability-centered maintenance) gives a framework for thinking about failures. There are also industry-specific failure code libraries (for example, the aviation sector has the ATA codes for systems and failure descriptors, and healthcare maintenance might use standards that include common biomedical equipment failure codes).
   
8. Include Both Technical and Human Factors: Remember that failures can be due to human error or procedural issues too. A mature failure coding system mostly includes codes for things like “operator error” or “improper installation” if those are relevant. It can be sensitive to assign blame via codes, but if done in a just culture way, this data is valuable.
   
9. Regularly Review and Optimize Codes: Over time, you might find some codes that have never been used. You can remove or consolidate them. New failure modes might emerge that need codes. Set up a periodic review, perhaps annually, of the code system. Look at how often each code was used and if there was any ambiguous usage. One best practice is to review a sample of completed work orders to ensure the coding quality is good. If people are misusing a code, clarify the definitions. Keep the library “clean” so it continues to be effective.
   
10. Leverage Technology Aids: Modern computerized maintenance management systems (CMMS) have features to make coding easier – like cascading drop-downs (you pick a problem, then it only shows relevant causes for that problem), or even suggestions based on text in the work order. There are NLP-based features with which the system reads the technician’s notes and suggests failure codes. Implement such tools to speed up and standardize your failure coding process.
    
11. Integrate with Workflow: Make failure coding a natural part of the workflow. For example, if you have a work order template for a breakdown, have fields for failure codes visible and in logical order (first describe the problem, then the cause, then the action). If paper forms are still used in the field, include a section for failure codes so that they get entered into the system. By integrating it, it doesn’t feel like an extra task – it’s just part of closing the job.

Understanding Common Failure Code Categories with Examples

Following are some of the most-used failure codes in maintenance. These failure codes provide all essential elements to capture issues and help build a comprehensive problem-solving framework in maintenance operations.

1. Mechanical Failures:

• WER – Wear: Normal wear and tear leading to failure.
• FAT – Fatigue: Material failure due to repeated stress (e.g. metal fatigue crack).
• MISAL – Misalignment: Misalignment of components causing failure.
• OVH – Overheating: Mechanical component overheated (e.g. bearing overheated due to lack of lubrication).
• FRZ – Frozen: Component seized or stuck (literally frozen or metaphorically).
  

2. Electrical Failures:

• ELC – Electrical failure: General electrical malfunction, like a blown fuse..
• SHT – Short circuit: Electrical short, such as a short in a power cable.
• OPN – Open circuit: Broken wire or connection, e.g., a severed control circuit wire.
• PWR – Power supply issue: Power supply problems like voltage drop
• SEN – Sensor fault: Faulty sensor providing false readings, such as temperature misreadings.
  

3. Fluid Leaks/Pressure:

• LEK – Leak: Fluid or gas leakage, such as an oil leak in hydraulics.
• PLU – Plugged: Flow restriction (e.g., filter or pipe blocked).
• PRV – Pressure Relief: A pressure relief device opened (could indicate an overpressure event).
  

4. Instrument and Control:

• CAL – Calibration issue: Instrument out of calibration, like a miscalibrated flow meter.
• AIR – Abnormal instrument reading: False alarm, e.g., incorrect temperature readings.
• LOGIC – Control logic error: PLC/DCS logic issue or programming bug.
• COM – Communication fault: Network or signal lost
  

5. Structural/Physical:

• COR – Corrosion: Material degradation due to chemical reaction.
• STR – Structural: Physical damage to structure or frame.
• BRK – Breakage: A part broke (could be generic if not captured by fatigue or overload codes).
  

6. Human/Process Causes:

• OPS – Operational error: Wrong button pressed, improper use.
• MTCE – Maintenance error: Improper reassembly, left tool inside.
• DOC – Documentation/Procedure issue: Procedure was wrong or not followed
  

7. External Causes:

• PWRFAIL – External power failure: Loss of external power, causing downtime.
• ENV – Environmental: Weather-induced (lightning, flooding).
• QCAL – Poor quality part: Premature failure of parts due to manufacturing defects.

And action codes might include:

• REPAIR – Repaired (in-place fix, e.g., adjusted, welded, etc.).
• REPLACE – Replaced component.
• CLEAN – Cleaned (removed contamination).
• ADJUST – Adjusted settings/alignment.
• LUBRICATE – Applied lubrication.
• CALIB – Calibrated instrument.
• MODIFY – Modified design or configuration.
• VENDOR – Escalated to vendor/OEM for repair (if that’s a step taken).

Let’s present a few failure codes in a table form for clarity. These codes and descriptions are adapted from typical MRO contexts and examples. It’s important to note that the specific failure codes and categories will differ by industry and organization.

Code	Meaning	Description
LEK	Leak – fluid or gas leakage	Fluid or gas leaking where it shouldn’t.
WER	Wear – normal wear and tear	Failure caused by wear over time.
FAT	Fatigue – material fatigue	Crack or break due to repetitive stress.
ELC	Electrical failure – malfunction	General electrical malfunction/failure.
MEC	Mechanical failure – malfunction	General mechanical malfunction (breakage).
OPS	Operator error	Incorrect operation leading to failure (human error).
MISALG	Misalignment issue	Components misaligned (e.g., shaft misalignment) causing failure.
CON	Contamination	The presence of foreign material caused problems.
OVHT	Overheating	Excess heat caused failure (could be electrical or mechanical).
CAL	Calibration required	Out-of-calibration instruments led to issues.

Takeaway

Failure codes may appear to be a minor technical detail in the overall context of maintenance management, but they illustrate the essential principle that you cannot improve what you do not measure.

By diligently recording the “what” and “why” of each failure, maintenance leaders equip themselves with valuable, data-driven insights. The transition from reactive to proactive maintenance and also predictive maintenance relies heavily on information, with failure codes serving as a vital source of that information. All in all, if you aim for smarter maintenance and longer-lasting assets, make use of failure codes.