Rough idle specifically when the engine is warm in your 2016 Jeep Compass, accompanied by a P0505 code, indicates the idle air control system isn't maintaining stable engine speed at operating temperature. This condition differs from cold-start issues and points to specific component concerns.
Understanding P0505 on Warm Engine
P0505 indicates an idle air control system malfunction. When the problem appears only after warmup, it suggests components that function marginally when cold but fail when thermal expansion and operating conditions change.
Why Warm-Only Rough Idle
Cold engines mask some idle problems through increased fuel delivery and higher idle speed settings. As the engine warms and the ECM reduces idle speed to normal targets, marginal control issues become apparent. Heat-sensitive component failures also worsen at temperature.
Common Causes
Carbon buildup on the throttle body prevents precise air control at low openings. The throttle position sensor may drift when warm. Vacuum leaks can worsen with component expansion. Heat-related IAC valve or electronic throttle issues manifest at operating temperature.
Throttle Body Focus
The 2.4L engine's electronic throttle body accumulates carbon over time. When warm, thermal expansion changes blade-to-bore clearance. Carbon deposits prevent consistent positioning, causing the rough idle characteristic.