Cruise Control Accel Signal Malfunction
Your cruise control's accelerator signal isn't communicating properly with the engine computer. It's like your cruise control's gas pedal button is sending a garbled message that the car can't understand.
The ECM monitors the voltage signal from the cruise control accelerate switch circuit. It expects a clean digital or analog signal within a specific voltage range when the cruise accel button is pressed. If the signal is absent, stuck, or out of range, the ECU triggers this fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Cruise Accel Switch Voltage | 0V (off) or 5V (on), clean transitions | Floating voltage, no signal, or constant high/low state |
| Signal Continuity | Stable signal for >200ms when button pressed | Intermittent signal, noise, or open circuit |
Code P0571 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, P0571 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.