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Can someone help me figure out where this connecter goes? This is a deleted 2011 Q7 TDI (CATA). The parts diagram says it's for.water temp sensor, but for the life of me I can't find the sensor.
There's a coolant line running across backside of the engine. As you can see from above photo the harness lead is pretty taught and runs a straight line to it basically. This is the coolant temp sensor that provides the data feed used by instrument cluster gauge, etc.
I would suggest you swap the rear, engine coolant temp sensor out while you got the car apart and can get at it easier, IMO. When I ordered coolant sensors online they were very inexpensive at under $10 each. There were considerably more expensive to buy locally (for such a generic sensor), and Audi's price was 500% markup on it.
Another thing to consider doing while it's apart already is that oil separator/PCV unit that sits right at the very, very way-back of the engine in the valley where you can't get at it unless you've removed literally everything.
Just as a side-note to help others, your pic offers a great view of where the brake booster to engine vacuum line connection is located on the firewall on a LHD car. On a RHD car it would be on the opposite side, etc. In this pic of your 2011 TDI it is located top center-right in pic and it ducks through the plenum and runs back across to the brake servo/brake booster. This looks just slightly diff than on my '10 and the hose from engine vac side routes differently on the later, Gen 2 TDI motors, but it all meets up in same spot basically, which is the important point of reference.
The bottom side of that connection (brake booster/female side) is what deteriorates from heat cycling and eventually cracks creating a vacuum leak....related to low or squishy brake pedal and braking issues, etc.
Last edited by '10Q7TDI_Prestige'; Jun 12, 2025 at 12:45 PM.
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Engine harness connector identification
