Hello all,

In my '01 Civic the connector pinout shows that the heaters for both of my narrow band 02 sensors are duty controlled. Under what conditions is the heater not operated at 100% capacity? How does the ECU know when the sensor is warmed up?

Sam

 

I'm going to take an educated guess at this.. But I would have to say that when the 02 sensor is hot enough the resistance changes between the heater wires "+12 and A6 on OBD1"

One way to investigate this is wire up a DMM between +12 on the ecu and the pin A6 equivalent on the OBD2 ecu and look at voltage from a cold engine to completely warmed up.. you could also measure resistance across the heater element from a cold to a warmed up engine.

Its possible once the ECT is up to temp the o2 isn't getting heated anymore.. since I could only assume that honda uses ECT to tell if the engine is warmed up enough.. But again I'm guessing at most of this stuff, I personally don't have my ecu control the 02 heater, but then again I have a obd1 car and its controlled by the plx-M300 and its also a wideband.

There really isn't any OBD2 tuning for hondas, everyone converts it to obd1 and uses some other tuning method like chrome/neptune/hondata/ectune... I honestly don't think there is much of any way to find out your answer unless you have the ability to log OBD2 data from a scantool or something..

Why would you be curious about this?

 

An unheated O2 will cool off quickly at idle.

 

Thanks so much for your ideas! I guess the fun things always take more work.

I'm installing a Megasquirt controller. I have it and half of the wiring harness adapter built and sitting on my desk, but this is one of the kinks to work out before install.

It looks like the default MS install has the heater running continuously, although maybe it runs only when the idle valve is open which would make sense given the insight of the following post. Seems like a fair compromise. I'll try to clarify that bit with other users.

Sam

 

Well test it, I wouldn't be the least surprised if the o2 heater was always on.