MAP Sensor Port Cover

The HOLLEY MAP Sensor Port Cover (HLY300-251) is a precision male push-on MAP sensor plug engineered for GM LS-series engine fuel injection systems. This aluminum component provides a sealed connection at the manifold absolute pressure sensor port, preventing vacuum leaks, fuel vapor ingestion, and contaminant intrusion that can compromise engine tuning and fuel economy. The black anodized finish resists corrosion while maintaining a clean OEM appearance under the hood.

Manufactured from aluminum and finished with black anodizing for durability, this MAP sensor cover includes factory-spec hardware and an integrated O-ring seal that ensures a secure, leak-free fit on LS-platform sensor ports. The male push-on design requires no threading or adapters—it seats directly onto the female port fitting found on most LS block applications. The O-ring seal is critical for preventing parasitic vacuum leaks that would allow unmetered air into the intake manifold, causing the ECU to run rich and affecting cold-start performance and idle quality.

LS-series engine builders, performance tuners, and restorers use this cover when disconnecting MAP sensors for diagnostics, sensor replacement, or during custom intake manifold fabrication. Any open sensor port on a running LS engine will introduce uncontrolled vacuum signals and false air mass readings. This cover solves that problem during testing, troubleshooting, or temporary sensor removal. The compact 3.5 x 1.2 x 5-inch form factor fits in tight engine bay spaces without interfering with intake runners, throttle bodies, or adjacent vacuum lines.