I have a honda civic 98 that shows rpm speed, but not the mph speed. I have tried almost everything to fix this problem I swapped the speedometer, I also tried swapping the speed sensor, still did not fix the problem. I am starting to believe maybe a wire is not connected? I checked the fuse and its still good. I also heard a comment that if your transmission has too much oil it can cause this, but im not 100 percent sure thats true, but my transmission does have too much oil on it. I will try to fix this issue when I have time. Any ideas of what the problem could be?

*Update: Just figured out rpm works with distributer and mph is from VSS. Maybe the VSS doesnt like too much oil? Ive changed the speed sensor like 3 times. 1st time it was going crazy, 2nd working for a while went crazy again and does not move at all now 3rd tried one didnt work and tried another one didnt work. I will get another VSS if I have to.

 

Automatic or manual transmission?
Did you buy an OEM, aftermarket or used speed sensor?
Honda used two different OEM manufacturers for both the automatic and manual speed sensors... you have to make sure you have the correct one. Do an online search via Honda parts dealers using the VIN number.
Aftermarket/Ebay are crap and will not last or work correctly.
Another way is pull one from a junkyard from same year and transmission type and match it up to the original (if you still have it).

Other possibility is odometer cable is broken or this: https://honda-tech.com/forums/honda-...r-fix-2792878/

 

Does the odometer turn? It is driven by same signal from the VSS.

Is the CEL on?

Fuse 15 problem or corroded VSS plug will make the VSS not produce a signal.

 

I was about to edit my post to include this as it happened to my 98 EX coupe (automatic). I replaced the VSS with a one I pulled from a junkyard that was in great shape. It worked well for three months and then stopped working so, I sprayed some electronic contact cleaner + lube in and on the harness clip and sensor and it's been working fine since (four months). To note: it was raining heavily for three days when the salvaged replacement part stop working and humidity most have caused poor electrical contact.