CID High
The ECU detected that a command interface (CID) signal is reading higher than expected, like a volume knob stuck too loud. This typically indicates a wiring short, sensor malfunction, or ECU communication problem.
The ECU monitors the CID (Command Interface Data) signal voltage or signal strength from various control modules. When this signal exceeds the maximum acceptable threshold, it indicates either a short-to-voltage condition, noise interference, or a faulty control module sending erratic commands.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| CID Signal Voltage | 0.5–4.5V (module-dependent) | >4.8V or continuous high state |
| CID Communication Frequency | Expected pulse pattern | Excessive or abnormal signal activity |
Code P1223 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, P1223 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.