Standard Ignition AS4 Manifold Absolute Pressure Sensor

Manifold Absolute Pressure Sensor for GM Applications

Standard Ignition AS4 is a manifold absolute pressure sensor built for precise engine load measurement and stable long-term operation. It is a direct-fit emission control sensor for a wide range of Buick, Chevrolet, GMC, Pontiac, Oldsmobile, Isuzu, Geo, and related GM vehicles.

With a female 3-terminal bullet connection and plug-in female connector design, AS4 is suited for service work where accurate MAP signal output and dependable electrical connection matter. This Standard Ignition AS4 MAP sensor is used across applications such as the Chevrolet Tahoe, GMC Yukon, and Buick Regal.

Key Features

• Manifold Absolute Pressure Sensor for emission control and engine management systems
• Female connector with plug-in design for straightforward electrical connection
• 3 female bullet terminals for the specified application interface
• Engineered for precision performance and long service life
• Manufactured with in-line and end-of-line inspection from raw material through packaging
• Broad vehicle coverage across many GM passenger and commercial applications

Detailed Description

Standard Ignition AS4 is engineered to deliver accurate manifold pressure input to the engine control system, helping the vehicle computer calculate load and adjust fuel and spark strategy. This matters on vehicles such as the Chevrolet Express 2500, GMC Savana 3500, and Pontiac Grand Prix, where a stable MAP signal supports consistent drivability and emissions performance. The AS4 part number is also referenced in service and interchange listings for multiple OE and aftermarket applications.

This part cross-references Bosch 18003 and Dorman - HELP 74413 for the same application.

What It Helps Address

• Erratic idle caused by inaccurate manifold pressure readings
• Hard starting or extended crank conditions related to faulty MAP input
• Reduced fuel economy from incorrect engine load calculation
• Check engine light concerns tied to MAP sensor circuit faults
• Driveability issues such as hesitation, surging, or poor throttle response

Installation Notes and Tips

Verify connector style, terminal layout, and OE reference before installation. AS4 uses a female connector with one plug-in connection and 3 female bullet terminals, so matching the harness and sensor interface is important for proper fitment. Confirm the vehicle application against the listed year and model coverage, including Buick Park Avenue, Chevrolet C1500 Suburban, GMC Yukon, and Pontiac Bonneville.

After installation, clear diagnostic trouble codes if present and inspect the intake and vacuum system for leaks that could affect MAP sensor readings. For best results, compare the replacement sensor to the original unit before final assembly.

Quality Assurance

Standard Ignition states that its manufacturing process includes robotics for precision assembly and 100% in-line and end-of-line inspection. The AS4 MAP sensor is produced under controlled manufacturing conditions to support consistent quality from component sourcing through finished packaging.