Uncle George

I have a '98 Civic LX sedan with motor D16 Y7, 48.000 original miles. CEL comes on. I unhook battery to reset it. CEL goes out and stays out for a few days of driving and then back on again. After doing this a few times, I paper clipped the connector under the dash and the CEL flashes code 41 (primary oxygen sensor-heater circuit malfunction). Unhook battery again and again light goes out only to come on again after a few days of driving. This particular sensor was replaced at 25,000 miles by Honda. The repair receipt gave code 0135 (primary oxygen sensor-heater circuit malfunction) which is the same as the code 41. At the time that seemed to fix it as no CEL again for 23,000 miles. But here we are again with the same problem. I read more than a few posts that said they changed out the sensor to fix a code 41 problem and it didn't fix it. Still got the code 41 flashed.

So, my diagnosis is that it is not the sensor but some sort of loose or faulty connection specifically having to do with the power to the heater part of the sensor. The reason I say that is that it seems to be intermittent. The malfunction seems to last only long enough to cause the ECU to throw the code 41 as the ECU can be reset very soon after and there is no further code and ready to drive.

I must say that I realize that it cound be a circuit malfunction with in the heater part of the O2 sensor but I must also say that I am retired and on a fixed income so I can't go out and buy expensive parts that I may not need just to see if it fixes it. Unfortunately I am very inexperienced when it comes to auto electrics and electronics and wiring and such. So far I figured I need to find out where those four little wires that come out of the sensor go to and which one does what. Thanks to a post on this forum I did find the following and I hope I got it right.

White wire/O2 Sensor signal/ goes to D14 on the ECU
Black wire (underneath the green wire on the OEM plug-in)/HEATER CONTROL/ goes to A6 on the ECU
Green wire/Sensor Ground (I suppose this is ground for the sensor and heater)/goes to D22 on the ECU
Black wire (underneath the white wire on the OEM plug-in)/O2 Sensor 12v power/goes to A25 on the ECU

Now that I have this info I am not sure what to do with it. I assume that I can access the ECU and locate the terminals mentioned above. So what do I do then, pull them off one at a time and slap them around, scream and plead with them and then reintstall. Don't know how to check to see if they're okay since they probably are okay at the moment as it is not throwing code. Only intermittently. I am puzzled as what to do. I don't have a multi-meter and have never used one so that makes me a bit unconfident about using one to check the circuits. But seems like I could check them with a multi-meter and still find everything okay or is there someway one of those meters will expose an intermittent short or disconnect.

I have posted on other forums but have gotten zero help. Have seen some posts on this forum that leads me to believe there are some folks posting on here that know their stuff when it comes to these electrical mysteries. Please can you spare me a bit of your time. This has become mighty worriesome. Thanks, uncle george

1750cc

i think this is just a small problem, if it throws a 41 code every now and then, there are only 3 possible problems.

1. bad sensor (most probable)
2, faulty wiring
3. stupid ecu (rarely happens, but still a possibility)

maybe there is too much carbon in your exhaust that it kills the o2 sensor, o2 sensors has a lifetime, bad o2 sensors most likely affect your fueling and you might run a little richer...

jdm 1080p

i have same problem but when i reset the ecu... it doesnt throw a code untill i start it then code 41 is back on?

Former User

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