Speed Control Unable to Hold Speed
Your cruise control can't maintain the set speed because the engine isn't responding properly to speed corrections. It's like trying to hold a steady speed on a hill but the gas pedal isn't cooperating.
The ECU compares actual vehicle speed (from the speed sensor) against the target cruise speed and adjusts throttle position accordingly. When the engine can't hold speed despite throttle commands, the ECU detects a deviation beyond acceptable tolerance and sets this fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Speed Error Tolerance | ±2 mph of set speed | >±5 mph deviation for extended period |
| Throttle Response Time | <500ms to reach target position | >1000ms or no response |
Code P1575 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, P1575 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.