Hello, I have a Mazda B4000 2wd pick-up. The check engine light is on and the abs light is also on. The speedometer does not work at all.

I checked the codes with my reader. It's saying P0500. Which means I have a faulty abs speed senser.

The light was on a couple a weeks ago when the speedometer was working, but it was running rough. It still running rough but only seems to run rough at a certain rpm. (a little above 1500 rpm) so, I checked the codes and says I have a misfire with two spark plugs.

So, I changed all spark plugs & wires. But it still does the same thing.

I have not put a new abs speed senser in yet. But I was wondering if this could be the cause of the running rough. This seems highly unlikely but I really do not know what this sensor does.

Anyway, I checked it tonight and it's not reading the misfire codes, but still reading the abs speed sensor code.

Could this be my whole problem, Or is this something else?

 

A abs code would not be the reason for a rough running engine. A abs speed sensor is a wheel speed sensor which is for reference for the system to know which wheel is decelerating irrationally quick compared to the others. What year is your truck and what is the engine? That would be very useful information. If it is a fuel injected engine I would try cleaning the maf sensor with maf sensor cleaner ( on how to do it). Also no matter the engine just replace the pcv valve, they're really cheap and also replace the air filter if it is dirty.