How to Replace an Air Injection Pump Filter

The air injection system introduces oxygen into the exhaust to reduce emissions. The system consists of a pump (either electric or belt driven), pump filter, and valves. Intake air enters the pump through a centrifugal filter located behind the drive pulley. When the engine is cold, the powertrain control module (PCM) controls the diverter valve to send pumped air to the exhaust manifolds. After the engine has reached operating temperature, it diverts air to the catalytic converter.

Your air pump filter may be failing when the engine is functioning sluggishly and there is a noticeable dip in performance. You may also notice poorer fuel economy and a rougher idle overall, since the air pump filter cannot adequately provide airflow to the engine. If these symptoms appear, you may need a new air pump filter.

Part 1 of 2: Remove the old filter

Materials Needed

  • Needle-nose pliers
  • Protective gloves
  • Ratchet
  • Repair manuals
  • Safety glasses
  • Wrench

  • Note: Be sure to put on safety glasses and protective gloves to keep from injuring yourself during the replacement process.

loosening the smog pump pulley bolt with a wrench

Step 1: Loosen the air pump pulley. Loosen the smog pump pulley retaining bolts with a socket or wrench.

removing the serpentine belt

Step 2: Remove the serpentine belt. Make sure there is a belt routing diagram under the hood of your car or take a picture of the belt with your phone prior to removal.

This way, you will know how to reinstall the belt. Remove the serpentine belt by inserting a ratchet end into the square slot on the tensioner or by placing a socket on the pulley bolt head. Push the tensioner away from the belt and slide the belt off the pulleys.

  • Note: Some vehicles use a v-belt instead of a serpentine belt. With this set up, you will need to loosen the pump mounting bolts and adjustment bracket. Then, move the pump inward until the belt can be removed.

removing the smog pump pulley by hand

Step 3: Remove the air pump pulley. Remove the pulley retaining bolts completely and slide the pump pulley off the mounting shaft.

removing smog pump filter with needle nose pliers

Step 4: Remove the air pump filter. Remove the air pump filter by grasping it with needle-nose pliers.

Do not pry on it from behind as the pump may be damaged.

Part 2 of 2: Install the new filter

Materials Needed

  • Needle-nose pliers
  • Ratchet
  • Repair manuals
  • Wrench

Step 1: Install the new air pump filter. Place the new pump filter in position on the pump shaft in the reverse of the way you removed it.

Put the pump pulley back on and tighten down the bolts evenly to properly seat the filter.

Step 2: Reinstall the serpentine belt. Reinstall the serpentine by moving the tensioner so that the belt can be slid back on.

Once the belt is in place, let go of the tensioner. Double check belt routing against the diagram you obtained in the first step.

  • Note: If you have a vehicle with a v-belt, move the pump inward so the belt can be installed. Then, tighten down the pump mounting bolts and adjustment bracket.

Step 3: Tighten the pump pulley bolts. With the belt in place, tighten down the pump pulley bolts completely.

You now have a new, properly functioning air pump filter installed which will be a huge boost to your engine’s performance. If this seems like a job you’d rather leave to professionals, contact one of YourMechanic’s certified technicians, who can come to your home or place of business and perform a replacement.


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