I installed the Defi D-series egt gauge in my STi a few weeks ago. The gauge was believed to have a short because the temp would never rise and the lighting would flicker. I went back and checked all of my wiring and did a continuity check on the power wiring harness and the sensor harness. The wires all checked out ot be fine. On the gauge itself, when it was all lit up and the needle resting on "0" ( yes, the car was running ) I could move the wiring in the back of the gauge and thats when the gauge would flicker and the needle would sweep full range and return to rest. I called the dealer I got it from and told them what all I had done on the install and troubleshoot and we both had the same hypothesis.......bad gauge. I returned the gauge to my dealer and they returned the gauge to Defi. Defi tested the gauge and claim nothing to be wrong. I got the gauge back today, and I still have the same problem. Any ideas?

I'm still stuck at a bad gauge because of the fact that the gauge lights up and will make a full sweep with the engine running but the temp never rises and the gauge still flickers when moving the wiring on the base of the gauge where it connects. :confused:

Make sure you have a good ground. Bad grounds can cause funny things to happen. Also, it sounds like the wiring from the guage to the sensor could be a little borked. The guage is functioning normally, but not getting a signal to tell it where to be at.

The ground is good, I used the same grounding area that I used for the stereo. Not the same point though. If there was a ground issue I would be having noise problems in the stereo as well since that is more sensitive to grounding issues. I did call the dealer back today and explained the problem again and we're still stuck on an issue with the gauge being bad or possibly a short in the sensor wiring that is only acting up when the wiring is moved. I'm leaning more towards the gauge and a bad solder joint that is being broken upon movement of the wires. That still wouldn't account for the gauge not reading the temps.....or would it?

well then maybe you arent getting readings because the probe is bad?? that could be something to check out... sounds like a difficult situation...

Are you wiring it with crimp connectors? sometimes they don't make good contact onto the wire and can give the syptoms that you describe.
Another possibility. Where did you pick up the + feed. I have met some cars where this is from a bi-metalic voltage stabiliser. This is rather like a flasher unit. It works OK on gauges with a slow response but fast ones can read the supply fluctuation. I don't know if the Subaru has that system.

John

Yes, I did use solderless connectors and I used the power and accessory wires from the factory stereo harness. The gauge isn't using enough current through the 22 gauge wire for there to be an issue with the power there. The factory wiring supports a head unit and the gauge without there being any current issues.