Hello all, I'm having a rather silly problem with an OBD1 B18B in my EF sedan. I've had 3 MAP sensors and they all output 0.3-0.6V key on engine off. The car does not start with any of them plugged in, but will run with poor drivability when they are not. I have verified that it's getting 5.0V from the power wire and continuity to the thermostat housing on the ground pin. I've also been able to verify this behavior with a bench power source. Is it possible that I've gotten 3 bad sensors in a row or could there be some other wiring issue at play that I don't know about?

 

The original MAP sensor wiring for your EF Sedan is on the firewall... are you still plugged in there ? Have you checked continuity between the signal pin at the MAP sensor plug and the proper location at the ECU plugs ? If you are buying Genuine MAP sensors from your local Honda parts department, three bad brand new MAP sensors is impossible. However, if you are getting them from a local auto parts store, EBay or Amazon... those are all junky or junkier, so all bets are off.

 

using the one on the throttle body thankfully! I've actually been curious if I can just pull that control box off fully now (converted to OBD1 with an aftermarket harness). I do throw a map code when it's unplugged, and although it's a cheap harness I verified as much continuity as possible before install. I can also replicate the behavior independent of the ECU with a bench power supply. Unless there's a way to fry these things by wiring wrong I'll guess an OEM sensor sensor probably fixes my problems