hamsammich

I've been searching audiworld for my symptoms but have been coming up empty-handed. Beginning just last week, my coolant temp gauge is not registering anything at all on my gauge cluster. When I start the engine, the needle moves the very slightest bit (like half a millimeter, I assume only because it's getting powered up) bit but it's still pointed on "C" regardless of how warm the engine gets.

When the car's fully warmed up, heat comes out of the vents just fine and when I put the CC into diagnostic mode, code 51 shows an ECT reading of 90. I had some coolant leakage problems a couple months back and had upgraded the ECT to the green one. I had held onto the original black one when I did the flange swap, so I plugged that in yesterday to see if my new green ECT is faulty, but got the same no-reading from my dash temp gauge. All of the contact leads on the ECT and ECT end of the harness are clean.

I have doubts that the thermostat is stuck open, as the heater blows hot air and the t-stat is less than 2 years old from when I did my timing belt. Can anyone offer any suggestions on what to do? Should I be checking the other end of the ECT harness wires? Where can I find that?

Many thanks.

quattro_blue

Run gauge (output test?) using VAG-COM, see if temp needle goes on 12 o'clock

kgardnez

I have verified by unplugging that code 49 is the right place to check and it's temp exactly matched with my gauge position.

Code 51 is a temp from somewhere else. and even while my gauge is being wacky it sits at 90deg.

hamsammich

Before I even started the cold car, I flipped to code 51 and watched it slowly climb for no reason, so that number is obviously wrong.

Flipped to code 49 and went for a fifteen minute drive. It didn't get past 47 degrees C. I left it idling in the driveway w/the heat off to try to get it warmer and the highest it got to was 57.

Looks like it's an open t-stat after all. Any idea what the range is on the dash gauge? I'm wondering if the needle won't budge til it hits 70 or so.

Thanks for your help!

hamsammich

I'm out of luck there. I've only got the free VAG-COM

hamsammich

Turns out both of the ECTs I tried were faulty. The green one was sending low values and the old black one (which was fine at the original time of removal) was intermittent. Got a brand new ECT in there and the needle now holds steady at 12 o'clock.

So much for the "improved" green ECTs.

Thanks everyone for your suggestions.