SULLAIR-STARTER-AUX-CONTACT critical Sullair WS Controller

Starter Aux. Contact — Starter Failed to Operate

The SULLAIR-STARTER-AUX-CONTACT (Sullair WS Controller) diesel fault code means: Starter Aux. Contact — Starter Failed to Operate. This is a critical severity code.

My Garage →
Keep driving?
Yes, but fix soon
DIY difficulty
moderate
Built for Diesel — Not a Car Reader
ANCEL HD7000 Heavy-Duty Diesel Scanner

A $30 car code reader can't do diesel. The HD7000 reads full-system codes and does parked DPF regen, idle/speed-limit, and service resets from the cab — on everything from a 6.7 Cummins/Power Stroke/Duramax pickup to Class-8 trucks (Detroit, Paccar, CAT, Volvo, Mack, International).

Check Price on Amazon

Affiliate link -- we earn a commission at no extra cost to you.

Lower-Cost Diesel Option
FOXWELL HD301 Diesel Truck Scanner
FOXWELL HD301 Diesel Truck Scanner

Full-system 6/9/16-pin diesel scan tool for Cummins, Paccar, CAT, Detroit and more — plug-and-play, no subscription. A cheaper way to read heavy-duty codes a basic OBD2 scanner skips entirely.

Check Price on Amazon

Affiliate link -- we earn a commission at no extra cost to you.

Common Symptoms

  • WS display shows Starter Aux. Contact; machine fails to start

Probable Causes (Ranked by Likelihood)

  • Starter failed to operate High
  • Faulty auxiliary contact High
  • Control wiring fault 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 starter and its control wiring.

  3. Check the auxiliary contact and its wiring.

  4. 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 aux contact for?

It is how the controller confirms the starter actually closed. If the starter engages but the aux contact does not report it — or the starter never engages — the controller flags this fault rather than running blind.

Sources

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

Explore More

Diesel home All diesel codes Heavy-duty Guides

Was this helpful?

Send this to whoever is fixing the truck — your tech, or the person asking what the fault means.