meternerd

2001 A6 2.7T. On my half finished cross country trip, my car has been failing to start after shutting it of when it's warmed up. Even if I shut it off and then immediately try to restart, it just cranks with no firing. If I let it sit for 15 minutes, it will try to start but idles terrible and puts out black smoke. Pushing on the accelerator does nothing. If I shut it off, then try again a few times, it will finally start and idle fine, then run perfect until the next time. When cold, it starts fine. No codes or CEL (I have a cheapie code reader/resetter).

I sure would appreciate any help, since we are trying to stop along the way to play tourist, but for now we either have to stay at least a half hour or somebody has to sit in the car with it idling while the other takes pics.

98Quattro

Sounds like your coolant temp sensor to me. Same problem and that is what fixed it for me.

meternerd

Thanks for the response.....can you help me with where it is on the 2.7T and is there a way to test it to make sure that is the problem?

98Quattro

On my 2.8L the temp sensor is locate on passenger side of engine at the back by the firewall. It sits on one of the coolant lines. I believe it's in the same location on the 2.7. You just have to remove a lot more things to get to it...such as the y-pipe, air hose, MAF possibly, etc.

Make sure to buy a new o-ring for the new temp sensor.

meternerd

Would a bad sensor cause the temperarure gauge to be wrong or erratic? Mine is rock solid mid-way on the gauge when warm. Is there a second sensor for the engine elecronics?

98Quattro

I believe so. When mine failed, the temp gauge didn't move at all from dead center.

thejulex

There are two separate temp sensors, one for gauge which never fails, and one for ECU which you cannot see unless using VAG-COM.

98Quattro

and those two are different than the coolant temp sensor in question...correct?

meternerd

Looking at the Bentley manual tells me that there is one 4 wire sensor with two elements inside....one for the gauge and fan and another for the ECU. I am going to order a VAG-COM setup, but I think I'll go ahead and order the sensor as well, only $24 plus shipping. I made it home, so now it's time to fix things right. Thanks again for all of the help.

meternerd

I got the new coolant temp sensor installed this morning and took the car out to warm it up 'till it was nice and hot. Turned it off and it started back up instantly. Thanks again for the help. Only took about 15 minutes to change the sensor.