btitus

ongoing problem that i haven't really done anything about yet:

temp gauge is behaving erratically -- moves around a lot, mostly reads low, but occasionally jumps up to where it used to read (middle). car seems to have coolant and heat, and it runs just fine.

was going to write it off to faulty gauge/cluster, however I've been using the diagnostic displays to look at the "digital" temperatures of both the coolant (49C) and the engine (51C) and I noticed that the temp gauge seems to follow exactly what the diagnostic is reporting.

Just wondering if perhaps this points to a sending unit (or even a thermostat?) as the likely cause. I'm guessing that the diagnostic reports the signal straight from the sending unit. So, bad sending unit = erratic temperature.

The engine temp diagnostic behaves just fine -- it warms up steadily without bouncing around at all.

I am tending to think the temperature being reported is not true, because a) there are 20 degree (C) swings in temp that seem impossible (although if thermostat is opening and closing erratically, I guess that could happen?) and b) while sitting this morning with the car off, but key on, I watch the temp gauge/diagnostic rise and fall repeatedly from about 60deg(C) to 80deg (C)... common sense tells me that can't happen with no water pump to circulate coolant.

so, the reason I'm picking this up again is that I'm now leaning toward a lease buyout. A month or two ago I was planning to just turn it in in April, so I didn't really care to diagnose this too far. oh, and warranty is up, so that's another reason I haven't pursued this. Any advice?

p.s. can anyone recommend a mechanic in the princeton/trenton area? would like to move on from the dealer once ownership begins.

MisterPTT

The temp would drop to 0 and the oil preassure warning icon would come on .... The happend randomly through out a drive, but mostly when stopping.

It didn't show a regular fault code. They had to look at some "special" codes in the cluster. I never did figure out what that ment ...

msauve

as it's been improved. The old one was about $40, the new part should cost about $5. A new o-ring is a good idea, and maybe a clip in case the old one gets broken when removing the sensor.

It's a 15 minute job, only about a cup of coolant will be lost if done correctly.

Coolant temperature sensor (new) 059-919-501A
Coolant temperature sensor O-ring N 903-168-02
Coolant sensor retainer clip 058-121-142

Jim TT

I have had many Audis wwith a Temp sender problem, not the TT but all the rest.