Troubleshooting S&B Particle Separator Fans

If your Particle Separator scavenge fans are not operating correctly — such as not turning on, running intermittently, or failing to ramp up in speed — start by watching this quick step-by-step video: Troubleshooting S&B Particle Separator Fans.

After following the steps, contact S&B Technical Support with your findings so our team can help resolve the issue.

S&B Technical Support
📞 (909) 947-0015
📧 customerservice@sbfilters.com

Fans Not Operating – Summary of Steps

  1. If 12 volts are present at the housing connector but the fans don’t spin, the fans or internal harness may be damaged and require replacement.
  2. If no 12V is detected, inspect and replace the fuse or relay if faulty.
  3. Verify that all bus bar connections are tight — vibration can loosen them during operation.
  4. Inspect the main wiring harness for cuts, pinching, or corrosion. Replacement harnesses can be ordered via the product page lookup.

Fans Running but Not Increasing Speed

Later model S&B control boards include diagnostic LEDs to simplify troubleshooting. Follow Step A if your control board has LEDs, or Step B if it does not.

Step A: Units with Diagnostic LEDs

  1. Key On: 1 green and 1 red LED should illuminate. Fans run at ~5% capacity.
  2. Engine Idling: 2 green and 2 red LEDs visible. Fans should run at ~25% (roll bar mount) or ~60% (fender well mount).
  3. At 4,000+ RPM: 3 green and 3 red LEDs visible. Fans should operate at 100% capacity.
  4. If LEDs do not appear or fans fail to ramp up:
    • Verify the Ignition Sensor is properly installed per your product’s install guide.
    • Take a clear photo of the sensor placement before continuing.
  5. If the problem persists, the ignition sensor may be faulty. Contact Technical Support with your photo.
  6. If LEDs show full status but fan speed does not increase, inspect for debris, a damaged harness, or broken fan blades. Use compressed air to clean as needed.

Step B: Units Without Diagnostic LEDs

  1. Key On: Fans should run at ~5% (roll bar) or ~20% (fender well).
  2. Engine Idling: Fans should ramp to ~25% or ~60%, respectively.
  3. At 4,000+ RPM: Fans should reach 100% output.
  4. If no speed increase occurs:
    • Verify Ignition Sensor placement per installation instructions.
    • Take a reference photo of the sensor before proceeding.
  5. If issues remain, the fault may be a failed ignition sensor, damaged fan, broken harness, or debris blockage. Clean with compressed air and contact support if unresolved.

Particle Separator Troubleshooting Diagram