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DTC DATABASE • OBD-II
P0685

ECM/PCM Power Relay Control Circuit Open

This page explains common reasons this code appears and what should be checked before parts are replaced.

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Common causes

What can trigger P0685?

  • ECU power relay fault
  • Fuse / wiring issue
  • Ignition feed fault
  • ECU power control issue
Typical symptoms

What you may notice

  • No-start
  • No ECU communication
  • Intermittent cut-out

Do not diagnose from the code alone

The code alone does not identify the failed part. Live data, wiring checks and manufacturer-specific subcodes may be required before replacing components.

Full scanLive dataWiring checksSensor plausibilityECU / module communication
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