High Air Filter Restriction

E172 – High Air Filter Restriction 

CID: 107-16 –    Engine Air Filter 1 Differential Pressure: High – moderate severity (2)    

Cause for an E172 Engine Air Filter Restriction

These events code normally indicate high air filter restriction.

The Engine Air filter restriction indicator will be illuminated. The action alarm will sound, action lamp will flicker. ENGINE WILL DERATE.

Recommended Steps for an E172 – High Air Filter Restriction

There will be a reduction in the engine’s performance if there is a restriction in the air inlet system.

  • Inspect the engine air cleaner inlet and ducting to ensure that the passageway is not blocked or collapsed.
  • Inspect the engine air cleaner element. Replace a dirty engine air cleaner element with a clean engine air cleaner element.
  • Check for dirt contamination on the clean side of the engine air cleaner element. If any dirt contamination is observed, contaminants are flowing past the engine air cleaner element and/or the seal for the engine air cleaner element.


Equipment filters working in low dust conditions last longer. Since it is impossible to visually determine when a filter reaches capacity, changing air filters too soon can result in unnecessary labor and filter costs. Conversely, in highly contaminated air, you may need to change filters earlier than scheduled to ensure full airflow and engine power.

Cat Air Filter Service Indicator

It is impossible to determine when a filter has reached capacity visually. Instead, the Cat Air Filter Service Indicator accurately reads a filter’s condition.

Any contamination in your air intake system can lead to reduced engine life. Dirt and debris in the air induction system may often result in loss of compression, premature component wear, or failure.

Routine SOS Oil Sampling can also help to identify dirt entry. Elevated Silicone (Si) levels in engine oil are often a result of dirt/contaminant entry, and can be an early indication that air intake system maintenance is required.

For more information on your air filter indicator and machine maintenance, refer to your operation and maintenance manual or contact your local H.O Penn representative.

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