I have a very low mileage 98 Civic sedan that I bought new and have faithfully maintained. Engine is D16 Y7. At 25,000 miles Honda replaced the primary oxygen sensor (code 0135 primary oxygen sensor heater circuit malfunction) as stated on the repair receipt. Was done under warranty, seemed a bit early for one to go out to me. So here we are at only 46,000 miles, just 21,000 miles later and yep, out of warranty, and I have the CEL shining at me again. I did the paper clip thing and I got a code 41 Primary Oxygen Sensor-Heater circuit malfunction. Same little rascal Honda replaced. 12,000 miles or 12 month warranty on replacement parts. [sm=sigh.gif] I can reset the ECU (battery disconnect/reconnect) and the light will go out only to come back on 4 or 5 days later, same code. Seems to me if the sensor was bad the light would come back on right after the reset and starting the engine. Earlier, Honda just replaced the sensor when they got basically the same code information. I had told them then that I had reset the ECU and it would clear the light only to come back on a few days later. Could it be that the wiring to the sensor could be faulty somewhere causing the heater to not activate (I believe that is the white wire on the sensor, green being the sensor) causing the code 41. I thought Code 1 was for the O2 sensor alone and indicated it was defective or had a bad circuit or unplugged. The code 41 is confusing me. Do I just replace the dang thing or do a bunch of checking for defective wiring. I do not own and have never used a multi-meter so that worries me a bit about checking out the wiring. Honda wants way too many dollars to look at it, let alone fix it ($85 just to do the paper clip thing and $221.00 for sensor alone not including labor). I am retired and live on fixed income. Also sure seems like these sensors are "malfunctioning" before their time. Seems like they ought to last at least 50,000 miles or more for sure. Thanks for any info that would get me back in shape. Oh yeah, does it hurt to drive it around seein's that the light goes off after the reset. The malfunction appears to only be temporary. Just don't want to go to Autozone prematurely if I have misunderstood or overlooked something. George [sm=helpout.gif]

 

well they are only guarenteed for 24K or 2 years..... but i would check ebay or go to a Honda Auto Recycling.. I had both of mine go out at the same time with the Heater malfunction which means that you may be putting out a little too much juice from the alternator. you may want to go to an auto parts store and they can check that for free. But as far as the O2 sensors for the one that is in the exhaust manifold is run 171 from dealer and the one in the cat runs 215 from dealer... so i suggest lookin on the internet and such.

 

Well so far very few responses here and elsewhere concerning this. I guess it is a bit of mystery even to the more experienced folks. What I have figured out so far is that more than likely I have a not so good connection somewhere on the circuit that either powers the heater or controls the heater or both I guess. I came across this information while trying to find out where the four wires on the primary O2 sensor go to or terminate at.

O2 Sensor output signal/white wire/ to D14 on the ECU
Heater control(on-off)/black wire(underneath the green one at the OEM plug-in) to A6 on the ECU
Sensor ground/green wire/ to D22 on the ECU
Sensor power(12v)/black wire/ to A25 on the ECU

Now that I have that information, I not real sure what to do with it. I have never looked at the ECU but from the information I assume that I can access the ECU and find somewhere on it or in it the terminals listed above. So what then. Unplug them one by one, slap 'em around, cuss 'em, and then hook 'em back up. I don't know how to check if the circuits are functioning correctly. Problem is they are functioning just fine most of the time. I get the ECL code 41 only every 4 or 5 days or so and then I can just reset it and everything's fine again for a few days. So the problem exists only momentarily, long enough to throw code, and then goes away. Arrghh. I have thought that possibly it may not be in any of external circuitry but rather inside the heater on the sensor itself. A new sensor should fix that. But I have ran across too many posts elsewhere that a new sensor did not fix the code 41. Puzzled to say the least. Can anyone confirm that the above information concerning the connections to the ECU are valid. Thanks, george