Volkswagen Cars 2000-05

Barometric Pressure Sensor

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Operation



The amount of fuel sent to the injectors is affected, in part, by the signals to the ECM from the altitude compensator. As altitude increases (decreasing air pressure) the fuel mixture will be adjusted accordingly. The altitude compensator continuously adapts the injected fuel quantity to the changing air pressure.

Removal & Installation



  1. Turn the ignition switch to the OFF position.
  2.  
  3. Disconnect the barometric sensor harness electrical connector.
  4.  
  5. Using a suitable tool, remove the barometric sensor.
  6.  
  7. Installation is in reverse order of removal.
  8.  

Testing



1.8L
  1. Disconnect the 3-pin harness connector from the barometric sensor.
  2.  
  3. Switch the ignition to 'ON', but Do NOT start the engine.
  4.  
  5. Switch the DMM to 'Voltage' measurement range.
  6.  



Click image to see an enlarged view

Fig. The 3-Pin barometric sensor connector (Passat 1.8L)

  1. Connect Multimeter between connector terminals as follows:
  2.  


    Terminal 1 and 3
     
    Terminal 2 and 3
     


The specification for each of these should be 4.5 to 5.5 volts.

  1. If the proper specifications are not obtained, connect a VAG 1598/22 Test Box to the ECM harness connector.
  2.  
  3. Check the wiring for an open circuit between the Test Box and the 3-pin harness connector. Check at the following points:
  4.  


    Terminal 1 & socket 61
     
    Terminal 2 & socket 62
     
    Terminal 3 & socket 67
     


For each of these checks, the specification should be a maximum wire resistance of 1.5 ohms.

  1. Check the wires for shorting to one another, and check the wiring for short circuit to battery positive (B+). The DMM should show infinite ohms.
  2.  
  3. If the wiring OK, replace the barometric sensor.
  4.  

 
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