Toyota Corolla trouble code P0505 ISC system malfunction with engine stalling on stop on Toyota Corolla

Some Toyota Corolla owners report experiencing issues related to the P0505 trouble code, which indicates an Idle Control System malfunction, leading to symptoms such as rough idle, stalling at stops, and a service engine soon light activation. These problems may arise from various causes, including a faulty or dirty Idle Air Control (IAC) valve, vacuum leaks, wiring issues, or a malfunctioning PCM. While the vehicle can still be driven unless the engine stalls or behaves erratically, owners may find driving difficult under such conditions. Repairing the P0505 code can vary in time, with simple fixes like cleaning the throttle body taking less than an hour, while component replacements may require more time. To diagnose the issue, it is recommended to scan for codes, inspect and clean the IAC valve, and check for vacuum leaks. If unplugging the IAC does not reset the code, it may necessitate the replacement of the IAC motor.