Mercury Idle Air Control Valve (IAC Valve)

The Mercury Marine 8M0188118 Idle Air Control Valve (IAC) is a genuine Mercury OEM engine management component designed for selected Mercury FourStroke outboard and MerCruiser MPI engine applications. The valve regulates the amount of air bypassing the throttle plate during idle operation, allowing the engine control module (ECM) to maintain a stable idle speed under varying operating conditions.

The IAC valve automatically adjusts airflow during cold starts, low-speed manoeuvring, gear engagement and changing engine loads. By precisely controlling idle airflow, the valve helps ensure smooth engine operation, reliable starting and consistent idle quality.

Common symptoms of a faulty idle air control valve include rough idle, stalling at low RPM, hard starting, fluctuating idle speed, hesitation and poor low-speed performance. Replacing a worn or sticking IAC valve can restore smooth engine operation and improve overall reliability.

The 8M0188118 valve is commonly found on Mercury EFI FourStroke outboards and selected MerCruiser MPI engines. This part has since been superseded by newer Mercury part numbers for many applications, making it important to verify fitment by engine serial number before ordering.

Manufactured to Mercury Marine OEM specifications, the 8M0188118 provides accurate idle control, dependable operation and long service life in demanding marine environments.

Superseeds: 897526T