Where is the B28 pressure sensor located in a Mercedes-Benz?
2 Answers
Automotive intake pressure and temperature sensors are generally installed on the intake manifold of the vehicle, positioned on the upper part of the intake manifold to prevent water accumulation. Typically, damage to high-temperature melt pressure sensors is caused by improper installation locations. Forcing the sensor into an overly small or irregularly shaped hole may result in damage to the sensor's diaphragm due to impact. Selecting appropriate tools for machining the installation hole helps control the hole's dimensions. Relevant information about the oxygen sensor is as follows: 1. Introduction: The oxygen sensor is used to detect the oxygen concentration in the exhaust and sends feedback signals to the ECU. The ECU then adjusts the fuel injection volume of the injector to keep the air-fuel ratio of the mixture near the theoretical value. 2. Function: The sensor measures whether there is excess oxygen in the engine's exhaust after combustion, i.e., the oxygen content, and converts this information into a voltage signal transmitted to the engine computer. This enables the engine to achieve closed-loop control targeting the excess air factor, ensuring that the three-way catalytic converter maximizes the conversion efficiency of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOX) in the exhaust, thereby optimizing the conversion and purification of emission pollutants.
I've been driving a Mercedes for a while now, so I'm quite familiar with the pressure sensor location. In most Mercedes models, such as the C-Class or E-Class, it's called the MAP sensor, primarily monitoring intake pressure, and it's installed near the engine's intake manifold. Open the hood, and when looking from the rear of the engine, it's usually close to the firewall or on the intake pipe. If you want to check it yourself, don't rush—first confirm the engine model, as the location might vary slightly between different engines; for example, in turbocharged models, the sensor might be closer to the turbo. If it malfunctions, the engine light will come on, and you might feel a lack of power. It's recommended to regularly scan for codes using a diagnostic tool to avoid any delays. When inspecting, be careful not to damage the wiring harness, as the engine compartment can get quite hot.
