Noobie1234

Hello All,

I recently bought a 2000 civic DX, it drives great! Last week I received a CEL I googled how to read error codes without the use of a code reading device. I found the blue plug and jumpered it as the instruction said. I received 4 long blinks and one short indicating 41 being Primary O2 Sensor heater. I gracefully changed out the sensor and unplugged the battery for about 5 minutes to reset the code. As soon as I turned the key it immediately returned. I then proceeded to O'Reillys where they received the same error code that I initially found and we reset the code. Guess what? after a minute the CEL returned. I really hate seeing a yellow light while I'm driving....any suggestions? BTW I did check #15 fuse and it appears to be good plus I checked the voltage at the plug and saw 12VDC....Thanks....

NOOBIE1234

ezone

Was that the ONLY code stored? What code number did the parts store come up with?

For future reference, OBD2 codes in the standard Pxxxx format are far easier to work with. Flash codes haven't been supported in over a decade. Get a cheap code reader or a scanner app or something.


Where's your original sensor at now? Did you test it, measure the resistance of the heater? (SM says 10-40 ohms)

What brand sensor did they sell you? What's the resistance of the heater circuit in it?

If the sensor is not right, get whatever brand your car originally had in it (Denso or NTK). Wire brush the rust off of old one to find the original name if you have to.


That's only half of the circuit.

Noobie1234

Thanks for responding and thanks for the help!!

Was that the ONLY code stored? What code number did the parts store come up with?

Yes that was the only error that came up. I didn't see the code number but the error that appeared on the screen was O2 heater sensor bank 2 error. I asked if that was the primary bank and she confirmed that it was.

For future reference, OBD2 codes in the standard Pxxxx format are far easier to work with. Flash codes haven't been supported in over a decade. Get a cheap code reader or a scanner app or something.

Thanks for the future reference.... I will look into that now since I own an older car. any recommendations on a scanner app?

Where's your original sensor at now? Did you test it, measure the resistance of the heater? (SM says 10-40 ohms)

I tested the original sensor and it measures 14 ohms across the 2 black leads. if that is the case I guess nothing was wrong with the sensor in the first place, but why did a get a CEL?...what else could it be?

What brand sensor did they sell you? What's the resistance of the heater circuit in it?

It was Bosch a sensor and it measured 9.8 ohms

If the sensor is not right, get whatever brand your car originally had in it (Denso or NTK). Wire brush the rust off of old one to find the original name if you have to.

The original was Denso but since if measured correctly there must be some other problem else where please advise.


That's only half of the circuit.

I measured one pin from pin to ground.

ezone

The car doesn't have a "bank 2"...so that throws everything into question.


No, but you can get the cheapest of cheap for probably less than $20. You get more functions if you spend more money.

There's more involved than JUST a sensor. You have plenty of wiring and a computer involved too.

I had guessed it was a Bosch then deleted that comment. Not a good choice IMO.



Got a service manual that tells how to diagnose the fault code?

What about the other half of the circuit that must be present in order to have a complete, working circuit?

A light bulb can't operate on positive alone. What else does it have to have in order to light up?



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