Overview
This document contains information on:
General
Location
Function
General
The pressure sensor downstream of the air filter detects the intake air pressure downstream of the air filter for the following tasks:
Monitoring of air filter soiling
Monitoring of boost pressure control
Plausibility check on pressure sensor upstream of throttle valve
Location
The pressure sensor downstream of the air filter is located in the intake air system between the air filter and the compressor wheel housing of the exhaust air turbocharger.
Structure |
1 | Pin 1: Ground connection |
2 | Pin 2: Signal voltage |
3 | Pin 3: Sensor voltage (5 V) |
4 | Test connection |
P07.04-A141-72
Function
The intake air pressure distorts a membrane that acts upon a potentiometer. This alters the resistance value of the potentiometer and thus influences the signal voltage, which serves to inform the combustion engine control unit about the air pressure downstream of the air filter.
If the pressure difference in relation to the atmospheric pressure is too great with a high engine load, the air filter is blocked. In this case, power output is limited by the boost pressure control, and also by the throttle valve if necessary.
The signal voltage from the pressure sensor downstream of the air filter is also used to monitor the boost pressure. Along with the signal voltage from the pressure sensor upstream of the throttle valve, it is used to calculate the ratio of pressure upstream/downstream of the exhaust gas turbocharger for the boost pressure control in the combustion engine control unit.
In addition, the signal voltage of the pressure sensor downstream of the air filter is required for the plausibility check of the pressure sensor upstream of the throttle valve.