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ISO 14224 Failure Mode Codes: Searchable Reference for CMMS Design

ISO 14224 defines a common vocabulary for collecting reliability and maintenance data, including a short list of three-letter failure mode codes. This lookup table lets you search those codes and use them as the starting point for the failure code list in your CMMS or ERP maintenance module.

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Code	Failure mode	What it means in practice	Typical equipment
AIR	Abnormal instrument reading	Instrument shows a false alarm, a faulty indication or a reading that does not match the process	Transmitters, gauges, sensors
BRD	Breakdown	Serious damage such as seizure or a major mechanical failure that stops the item	Pumps, compressors, gearboxes
ELP	External leakage, process medium	Process fluid or gas escapes to the outside	Pumps, valves, heat exchangers
ELU	External leakage, utility medium	Utility fluid such as lube oil, coolant or hydraulic oil escapes to the outside	Hydraulic units, gearboxes, coolers
ERO	Erratic output	Output is unstable, hunting or oscillating	Controllers, drives, sensors
FTC	Fail to close on demand	Item does not close when commanded	Valves, dampers, breakers
FTF	Fail to function on demand	Item does not perform its function when called on	Safety systems, standby equipment
FTO	Fail to open on demand	Item does not open when commanded	Valves, dampers, breakers
FTR	Fail to regulate	Item cannot hold or adjust the controlled variable	Control valves, regulators
FTS	Fail to start on demand	Item does not start when commanded	Motors, pumps, generators
HIO	High output	Output is above the specified level	Pumps, generators, drives
INL	Internal leakage	Fluid passes internally between zones that should be isolated	Valves, cylinders, heat exchangers
LCP	Leakage in closed position	Fluid passes through a valve that is commanded closed	Isolation and control valves
LOO	Low output	Output is below the specified level	Pumps, compressors, generators
NOO	No output	Item runs or is energised but produces no output	Pumps, sensors, power supplies
OHE	Overheating	Temperature exceeds the allowed limit	Motors, bearings, gearboxes
PDE	Parameter deviation	A monitored parameter drifts outside tolerance	Instruments, process equipment
PLU	Plugged or choked	Flow path is restricted or blocked	Filters, strainers, heat exchangers
SER	Minor in-service problems	Small defects such as loose parts, minor leaks or discolouration that do not stop the item	Most equipment
SPO	Spurious operation	Item operates without a command (false trip, false start)	Safety and control systems
STD	Structural deficiency	Cracking, wear, corrosion or loss of structural integrity	Frames, supports, vessels, pipework
STP	Fail to stop on demand	Item does not stop when commanded	Motors, pumps, conveyors
UST	Spurious stop	Item stops without a command	Motors, compressors, drives
VIB	Vibration	Vibration level is above the acceptable limit	Rotating equipment
OTH	Other	A failure mode not covered by the other codes	Any
UNK	Unknown	Failure mode could not be determined from the available information	Any

Summary of the commonly used generic failure mode codes. ISO 14224 is a copyrighted standard: buy it for the full taxonomy, equipment class tables and data-quality rules. Descriptions here are plain-language summaries, not standard text.

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How to use this table

Search by code, by symptom word such as leakage, or by equipment type. When you design failure codes for a CMMS, pick the subset that your technicians can actually tell apart at the machine. A list of 25 modes is usually the ceiling for a good drop-down: more than that and technicians choose the first item or Other.

Filter on a symptom word to see candidate modes
Keep the code and the plain-language name together in the CMMS drop-down
Export to Excel to review the list with your technicians
Remove modes that do not apply to your asset base

Failure mode, cause and mechanism are different things

A failure mode is how the item failed (for example INL, internal leakage). A failure mechanism is the physical process behind it (wear, corrosion, fatigue). A failure cause is the root reason (poor lubrication, wrong material, operating outside design). Mixing these in one code list is the most common reason failure data cannot be analysed later. Capture the mode at the work order, and the cause during the review of significant failures.

Mapping to ERP and CMMS fields

Most maintenance systems have a coded structure for this. SAP PM uses catalog profiles with code groups and codes for damage, cause and activity. Other CMMS products use problem, cause and remedy fields. Whichever you use, keep three separate fields for what was observed, why it happened and what was done, and map the ISO mode into the first one so cross-site reports line up.

Common mistakes

Teams copy a very long standard list into the system and then never use most of it. Others allow free text only, which makes Pareto charts impossible. A third mistake is treating the code as proof of root cause: the code classifies the symptom and does not replace an investigation. Review the unknown and other percentages monthly; if either is above about 15 percent of closed failures, the list or the training needs work.

Frequently Asked Questions

Do I have to buy ISO 14224 to use these codes?

You can use a simple failure code list without the standard, and this table is a plain-language summary. If you plan to share data with other sites or companies, or follow the equipment class tables and data quality guidance, you should buy the standard from ISO or your national standards body.

How many failure codes should a CMMS have?

As few as will still support analysis. Many plants do well with 15 to 30 modes, a short cause list and a short remedy list. Test the list with technicians: if two codes are routinely confused, merge them. Add detail only when someone will act on the report.

What is the difference between failure mode and failure code?

The failure mode is the concept of how the item failed. The failure code is the short label you store in the CMMS or ERP to record it. A good code list maps each code to a defined mode with a one-line description so every technician records the same thing.

Can I use these codes in SAP PM?

Yes. You can create a code group in a catalog (for example damage codes) and load the codes as entries, then assign the catalog to your notification and order types through catalog profiles. Plan the structure first, because changing codes after history exists makes trends harder to read.

If you want failure modes pulled from closed work orders in your ERP and ranked automatically, we can build that as a read-only report on your own data.

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