IDM_EN Circuit Failure
The engine's fuel injection timing control circuit isn't communicating properly with the engine computer, like a radio losing its signal to the broadcast tower. This prevents the injectors from firing at the right moments, disrupting engine performance.
The ECU monitors the Injector Drive Module (IDM) enable circuit for proper voltage and signal continuity. It expects a valid control signal between the PCM and IDM to regulate fuel injection timing. A circuit failure means broken wiring, loose connectors, or a failed IDM module.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| IDM Enable Signal Voltage | 4.5-5.5V with proper switching | Below 2V or open circuit detected |
| Signal Continuity | Continuous valid pulses | Intermittent or no signal |
Code P1680 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1680 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.