How did you go with this?

My bunky 97 GX foz has just developed a speedo prob. It is an electronic speedo. When I first get in the car it works ok for the first few minutes whilst still cold. As it warms up, it starts to fluctuate with about a 20k variance. After about 5 minutes or so (travelling at around 70km/h) it bounces from zero to 80 and then sits on zero. After it has been on zero for a while and I slow or stop, I often get the check engine light.

Does this sound more like a speed sensor or the cluster?

/csb.

Pretty sure all the white face ones were electric, must be a late 97 MY98, you could check the plug at the gearbox, maybe give it a spray with some lube, toward the front on the drivers side.

If your speedo is fluctuation it's either the cable or the gears in the bash have lost some teeth. Pull the cable out and turn it buy hand if it's boot turning smoothly then spray some penetrating lube down the cable. If not I'd be looking at the cluster. If you have electric speedo it's not Un common for the plastic speedo drive gear inside the gear box to flog out. If that's the case and you don't want to spend the money to fix it buy a sat nav

As mentioned mine is electronic. Currently relying on an app on my phone but I would like to fix it to stop the check engine light.

Anyone know if all Subaru speedo sensors are the same or are they different to suit different diff gears etc?

the sensor changes at some point, i think version 4 has the seal inside the box & version 5 & 6 have the seal as part of the sender itself, i remember having the remove the seal from my dccd box to fit the stock my99 foz gt sender (same as my99 gc8)

& yes there is a globe behind the light in the white faced gc8 dash, if you can't see your clock it will be blown