Preventive vs Reactive Maintenance: A Decision Matrix
Why this matters
Every shop runs on a mix of two modes: fix it when it breaks (reactive) and service it before it breaks (preventive, or PM). Reactive feels cheaper because you only pay when something fails, but the failure usually arrives at the worst time, takes out related parts, and burns a premium emergency visit. Knowing which mode a given piece of equipment deserves is one of the highest-leverage calls a tech makes. This card gives you a clean way to decide.
The two modes defined
Reactive maintenance means you wait for a fault, then respond. No scheduled visits, no proactive checks. You run the asset to failure.
Preventive maintenance means you service on a plan: clean, adjust, lubricate, tighten, and replace wear parts on a schedule before they fail. The goal is to catch the small problem while it is still small and to extend the service life of the whole system.
There is a third mode worth naming: condition-based maintenance, where you let measured wear signs trigger the work instead of the calendar. That is a refinement of PM and gets its own treatment in a separate article.
The cost picture nobody sees
The trap in reactive maintenance is the hidden cost. A motor that seizes does not fail alone. It can take out the part it drives, overheat a nearby control, and leave the customer without service until you can source the part. Add the emergency-rate visit and the collateral damage, and a reactive failure routinely costs several times what the same part would have cost replaced on a planned visit.
PM has a real cost too: the labor of the visit and the parts you replace before they are fully spent. The decision is not "PM is always cheaper." It is "for this asset, does the cost of planned service beat the expected cost of failure?"
Decision matrix
| Factor | Lean reactive | Lean preventive |
|---|---|---|
| Cost of failure | Low, isolated | High, takes out other parts |
| Failure consequence | Minor inconvenience | Safety risk or full outage |
| Redundancy | Backup exists | Single point of failure |
| Replacement cost | Cheap, fast to source | Expensive or long lead time |
| Failure warning | Sudden, no signs | Gradual, detectable wear |
| Access | Easy to reach later | Buried, hard to service |
| Duty cycle | Light, intermittent | Heavy, runs constantly |
When most rows point right, that asset earns a PM plan. When most point left, run-to-failure is the honest call and a PM visit is just selling work that does not pay back.
When to pick which
Pick preventive when failure is dangerous, expensive, or shuts down the whole job; when the part shows gradual wear you can read; when access is hard; or when the equipment runs a heavy duty cycle. A pump on a critical system, a control board on a high-cost unit, a valve buried in a wall: these are PM candidates.
Pick reactive when the part is cheap, easy to reach, fails without collateral damage, and has a backup. A simple indicator light, a low-cost filter on a redundant path, a fixture that fails gracefully: let it run.
The mixed reality: most systems are not all one mode. The right plan PMs the high-consequence components and runs the trivial ones to failure. Do not blanket a whole site with either policy. Walk it part by part.
How to present it to the customer
Customers hear "preventive maintenance" as "you want me to pay for work I do not need yet." Reframe it as risk: name the specific failure you are preventing, the consequence of that failure, and why catching it on this visit is cheaper than catching it as a callback. Tie it to their situation (a business that cannot afford downtime, a single unit with no backup) rather than a generic schedule. Honesty wins repeat work: tell them which parts you would let run to failure too.
References
- OSHA general industry guidance on equipment inspection and maintenance practice
- Manufacturer documentation: published service intervals and maintenance schedules for installed equipment
- Reliability-centered maintenance, trade-standard practice for matching maintenance strategy to failure consequence
- See related: Condition-Based vs Calendar-Based Maintenance; The Maintenance That Prevents the Emergency