96 Passat returned fuel question

TDI001

Member
Joined
Mar 5, 2005
TDI
96 passat blk
I have a 96 passat. The end of my clear-tube-returned line is connected to a T. The T directed the fuel to the fuel filter and to a sensor(?) near the rear of the airbox. The line from the sensor connect to the exhaust pipe. What is that sensor? Is is just a thing to help heat the fuel? Thanks for any info.
 

Lug_Nut

TDIClub Enthusiast, Pre-Forum Veteran Member
Joined
Jun 20, 1998
Location
Sterling, Massachusetts. USA
TDI
idi: 1988 Bolens DGT1700H
The "sensor" is a solenoid operated pump that squirts fuel into the catalytic converter. Why? Some theoretical calculation showed that the cat could cool down and become less effective. The raw fuel in the cat would burn and raise the cat's temperature back up to an effective level.
In practice the fuel was squirted into the cat at too low a temperature to burn. The raw fuel could create large black clouds under certain conditions. Talk about embarrasing! The intent was to reduce emissions, the result was an unbelievable increase in emissions.
The cat injector was left off the 1997 Passat. There is a VW service program (not a recall) to delete the operation of the injector from the 1996. Your's may have been done already.
There is also a low cost, at home, means of defeating the injector if the service work hasn't been done to yours yet.
Use the search feature located under the ad for the plate frame at the top of this page. Use "fifth injector" as the search phrase to get so much more information than you'd ever want.
 

TDI001

Member
Joined
Mar 5, 2005
TDI
96 passat blk
Thank you for the info
I knew that I would find the answer here. What a great forum.
 
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