'98 Mazda B2500 2.5L 2wd, Auto. My OBDII system isn't working right. The CEL is lit when the ignition is on, but it never comes on when any engine component is unplugged. All the tester states is "No codes present" I'm having rough idle/misfire issues. I've checked the code checker on another vehicle and it listed several codes for that vehicle. Please Help!
Additionally, I changed out the Engine Computer Box.
Your tester may be incapable of retrieving the codes.
Malfunctions with things like transmission, ABS etc can only be scanned with expensive tools that have more advanced functionality.
Hey MMJ! Maybe so my tester is a cheapo, but shouldn't the CEL come on when I unplug the TPS, or MAF, or anything else and then start it?
You would think so. All the OBD functions are contained within the main computer which you replaced.