IMCC Circuit Malfunction
Your engine's Idle Speed Control circuit isn't communicating properly with the computer, like a radio losing its signal. The ECU can't maintain steady idle speed because the control valve isn't responding as expected.
The ECU monitors voltage and current signals from the Idle Speed Control (ISC) valve or stepper motor to verify proper circuit operation. It checks for electrical continuity, correct voltage levels, and appropriate response times when commanding idle adjustments. If the circuit resistance is too high or the valve doesn't respond within expected parameters, a malfunction code is triggered.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| ISC Circuit Voltage | 4.5-5.5V with proper modulation | Below 3.0V or above 6.0V, or no response to commands |
| Circuit Response Time | Valve moves within 100-200ms of command | No movement or response delayed beyond 300ms |
Code P1568 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, P1568 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.