Cause
Failed ECM power relay
The relay holding the engine module powered — including for a few seconds after the ignition is switched off, so it can write adaptations and finish tests. A relay releasing too early means those are never saved, so the next start runs on defaults and feels like wear rather than an electrical fault.
Typically an easy fix. Often worth checking before paying anyone to look.
Codes this can cause (15)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0685 Engine Control Module Power Relay Control Circuit Open Likely for this code High
- P0686 Engine Control Module Power Relay Control Circuit Low Likely for this code High
- P0687 Engine Control Module Power Relay Control Circuit High Likely for this code High
- P0688 Engine Control Module Power Relay Sense Circuit Open Likely for this code High
- P0689 Engine Control Module Power Relay Sense Circuit Low Likely for this code High
- P068A Engine Control Module Power Relay De-Energized Performance — Too Early Likely for this code High
- P0690 Engine Control Module Power Relay Sense Circuit High Likely for this code High
- P2505 Engine Control Module Power Input Signal Likely for this code High
- P2507 Engine Control Module Power Input Signal Low Likely for this code High
- P2509 Engine Control Module Power Input Signal Intermittent Likely for this code High
- P2510 Engine Control Module Power Relay Sense Circuit Range/Performance Likely for this code High
- P2511 Engine Control Module Power Relay Sense Circuit Intermittent Likely for this code High
- P0657 Actuator Supply Voltage A Circuit Open High
- P0658 Actuator Supply Voltage A Circuit Low High
- P2506 Engine Control Module Power Input Signal Range/Performance High
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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