Compressor Discharge Temperature Switch (S3) Open — Overheat Shutdown
The DOOSAN-CODE-1 (Doosan/Ingersoll-Rand SECU portables) diesel fault code means: Compressor Discharge Temperature Switch (S3) Open — Overheat Shutdown. This is a critical severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
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Common Symptoms
- Machine shuts down and SECU display shows code 1
- Airend discharge may be genuinely overheated
- Will not restart until the S3 circuit closes
Probable Causes (Ranked by Likelihood)
- Airend discharge over-temperature — the S3 switch opens at 248°F High
- Faulty S3 switch Moderate
- Broken or chafed wiring between S3 and the SECU (wires W006 / W088) Moderate
Step-by-Step Diagnostic Procedure
This code set applies to SECU-display machines (7/51, 7/71, XP185, P260). Newer Tier-4-Final Doosan portables such as the P185WDOU-T4F use a DIFFERENT code set (CPR codes) — confirm which controller your machine has before acting on this page.
Rule out a genuine overheat first: check compressor oil level, cooler cleanliness and ambient conditions before treating this as an electrical fault.
Check continuity of wire W006 from S3 pin 2 to SECU controller pin 10.
Check continuity of wire W088 from S3 pin 1 to splice E16.
If wiring is continuous and the machine is not actually hot, replace the S3 switch (located in the discharge pipe from the airend).
Frequently Asked Questions
What does code 1 mean on a Doosan or Ingersoll-Rand portable compressor?
The SECU controller has detected an open S3 discharge temperature switch. S3 is the high-temperature shutdown switch for airend discharge and opens at 248°F, so the machine either genuinely overheated or the switch/wiring has failed. Code 1 shuts the machine down.
Is code 1 always an overheat?
No. The SECU only knows the switch circuit is open. A failed switch or broken wire (W006/W088 in the factory harness) produces the same shutdown as a real overheat, which is why the factory procedure checks circuit continuity before replacing anything. But rule out real overheating first — low compressor oil, a blocked cooler, or high ambient temperature will keep re-tripping a healthy switch.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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