Cruise Control Coast Signal Malfunction
Your cruise control's coast function isn't working properly—it's like a dimmer switch that won't send the right signal to turn down your engine speed. The ECU can't tell when you want to coast, so it can't execute that command.
The ECM monitors the coast control switch signal voltage and logic state from the cruise control stalk. It expects a clean digital or analog signal transition when the driver activates the coast feature. If the signal is missing, intermittent, or out of range, the ECU logs a fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Coast switch signal voltage | 0V or 5V (clean digital transition) | Floating voltage, stuck state, or no signal detected |
| Signal continuity/duration | Proper pulse or hold duration | Intermittent dropout or timeout error |
Code P0570 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, P0570 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.