So I'm quite unsure of myself but. I got a check engine light back in april. When I first checked it with the OBD II scanner the code that came out was P0500. My initial thought was to replace the VSS ( vehicle speed sensor) thinking maybe it went bad. But i continued to do further research. I found a post by Billman a few years back that if you have a yellow box, this could be a disrupting factor as to why this is happening because it is not able to translate your speed accurately. I'm running 4.77 gears, so should i just remove the yellow box entirely , but if i do my speedometer will be off like maybe 10mph. So if im going 50mph im really going like 60mph or something like that. I'm trying to get a better understanding on how the yellow box and VSS work together, so I can determine whether to remove the box or just replace the VSS.

- on a side note; the other day my vtec stop engaging. When i got to like 7k the car felt like it hit a brick wall. And i changed the oil 400 mi ago. Its still kinda brand new. So I'm thinking what ever is going on electrically is putting the cars computer in a safe mode that wont allow it to go all the way.

Please any advice or opinions that could help me on why this may be happening, id greatly appreciate it, Thank you!

 

Are all your yellow box connections soldered?

Twisting wires together and then using electrical tape or wire nuts won't cut it.

Solder that stuff and make sure your ground is 100%.

My yellow box has never given me any issues.

I doubt it's your S2000's VSS.

Yes, your car will go into a "limp mode" if it thinks it's revving to 7K and not moving.