Throwing P0500 code

I'll try to make this as short as possible although that will be tough.

Throwing P0500 code. Everything seems to be acting normal, reason I needed it fixed was for emissions to receive new registration sticker. 2005 TRD Tacoma 255,000 miles

Changed both front wheel sensor, and tranny speed sensor.
Didnt help.
Went to a mechanic he had a guy run a diagnostic on it ($300.00) he said the cluster panel was bad, ordered a used one hooked it up, throwing the same code. Took it back to mechanic had diagnostic guy look at it again, he said that cluster was bad. Ordered another used cluster put it in and it's still throwing the p0500 code. Does anyone else have any idea what else to try?

I talked to a guy at a custom stereo shop and he said that's one of the worst codes to have show up. He suggested I post here and see if anyone else has any ideas.
Hope to hear from some people with some ideas. Thanks a lot.

 

From my experience, codes rarely point to something directly. Instead, think of the code as saying that there's something wrong related to what the code is telling you.
Did you check the wiring? Following it back from the speed sensors. You may have a nick or gouge in the wire. Maybe a pin was not locked into the connector body and pushed out a bit. Did you check all 4 wheel speed sensors?
As an example....I had a P0420. Catalytic converter below effeciency threshold. The mechanic is adamant that I need a new cat and not 2 gaskets that actually fixed the problem.
Take your time, pay attention and you'll probably find something silly...
Good luck