Can someone tell me what this is?

this is the plug for the water in fuel sensor when they have it additional on the fuel filter housing, better your truck doesn't have it when they do they have a very bad design on the fuel route and usually the fitting before the housing ends up getting plugged up all the time. just one of those extra options that you can have on a vehicle not all come with them.

 

Nobody took the bait lol

 

Probably looking at cups and injectors again, tell the guys when they put these injectors in to tight the holddown at 20 and then 120 degrees final torque and it should be better, i havent had any problem so far, not neccessarily spec but it works.

 

i get this a lot, all my customers now all say the same thing, they dont mind paying to fix a problem but they know once they leave here the chances of them coming back for the same issue are slim to none, this is the reason i am usually so busy also i am a big believer that if i do something it is worth doing it the right way.

 

Lol.

 

Hello, that’s the spare harness for dual filters ( fuel filter and water saprater filter)
Volvo leaves free and hang on housing. You can see in pic

 

here's part numbers if you want to terminate that plug
20374157 - Cap
3963413 - Plastic Ring to secure it in place