CID Low
The ECU detected that a command signal to an injector or actuator is stuck at a low voltage level, like a light switch that won't turn fully on. This prevents the component from operating properly and triggers the fault code.
The ECU monitors the voltage output of a CID (Command Injector Driver) circuit that controls fuel injectors or similar solenoid devices. When the signal voltage remains below the minimum threshold required to activate the component, the ECU logs a fault. This typically indicates a wiring issue, short circuit, or driver circuit malfunction in the ECU itself.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| CID Output Voltage | 0-12V switching properly with rise time <1ms | Stuck low or fails to reach activation threshold (~5V minimum) |
| Command Signal Rise Time | <1 millisecond transition | >2 milliseconds or no transition detected |
Code P1224 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, P1224 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.