SULLAIR-LOW-SUMP-PRESSURE moderate Sullair WS Controller

Low Sump Pressure — Sensor or Start Fault

The SULLAIR-LOW-SUMP-PRESSURE (Sullair WS Controller) diesel fault code means: Low Sump Pressure — Sensor or Start Fault. This is a moderate severity code.

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Keep driving?
Yes, but fix soon
DIY difficulty
moderate
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Common Symptoms

  • WS display shows Low Sump Pressure
  • Machine may have failed to start or load

Probable Causes (Ranked by Likelihood)

  • Bad pressure sensor or connections High
  • Machine failed to start / build pressure Moderate

Step-by-Step Diagnostic Procedure

  1. The WS Controller is fitted to Sullair STATIONARY electric shop compressors. Portable towable Sullair units (185-class and similar) use different engine-driven controls and a different fault system — this page does not apply to them.

  2. Check the P1 pressure sensor and its connections and wiring.

  3. Confirm the machine actually started and loaded — a failed start reads as low sump pressure.

  4. Factory limits for this condition: P1 low limit 5 psig

  5. Per the factory manual: after resolving a fault condition, press the STOP pad to clear the FAULTED state. If the problem persists after the recommended checks, consult your Sullair distributor or factory service.

Frequently Asked Questions

What is the low limit?

Per the parameter table the sump pressure (P1) low limit is 5 psig across machine classes — below that the controller flags the condition.

Sources

This page is built from documented references. Verify against your own service info before repair work.

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