I have a 2001 2.8L A-6. Start it up and from the get go the temperature gage reads one dash past the midpoint. The AC works fine. Once the car gets warmed up the temperature gage goes all the way to the right. AC stops cooling and I get the over temp warning when the car really isn't overheating. Could this be a faulty temperature sending unit? Where is it located? Other info is less than 2 years ago had the timing belt changed, water pump etc. Thanks for the help.

 

99% it's the coolant temp sensor. You can change it yourself and it costs about $20-25. It's on the back of the engine, behind and below the top of the passenger side cylinder head. Pull the airbox pipe and mass air sensor off and look down. On your car it's probably the green sensor. The plug is on top of it. Make sure you also get a new retaining clip for it - it's plastic and will probably break when you remove it.

That sensor is notorious on the 2.8 and there's a DIY on AudiWorld or AudiDIY for changing it.

 

Actually the stock one has black connector. Updated replacement will have green connector.

 

Based on the A4, I wouldn't have expected that. My 99 AHA 30v already had the blue sensor which replaced the black one on the 12v cars. My buddy's 01.5 ATQ 30v came stock with the green connector so I assumed the A6 would be the same, given that the engines are the same.

 

Really appreciate the input. Thank-you.

 

Anytime and FYI in the future, since your A6 is a 2.8 30v you'll robably find a lot of useful tech info in the A4 section. Many of us also have that engine and there's a lot more traffic in that area.

 

How do you know the engine is not overheating? I have close to the same symptoms except on start the guage is all the way left. It quickly moves to two notches past center, AC stops cooling. It will go farther and eventually trip the overtemp warning light. I was thinking I needed a new thermostat, which really means water pump, timing belt, etc. Sure would be nice if all it needed was a sensor. I can bring the temp down some by turning on the heat all the way. Thanks.

 

Bob, I'm just assuming the car isn't overheating. It wasn't that long I had timing belt, thermostat, water pump replaced. I found out the dealer wants $40 for the sensor unless purchased over the internet. What a ripoff.

 

I suggest starting with the sensor. Cross your fingers your new thermostat didn't take a **** on you.

 

I got them crossed!