'98 Civic HX CEL - O2 sensor
 

Hello all,

I previously posted about my '98 HX poor FE: https://www.gassavers.org/showthread.php?t=9419

The general consensus was the primary O2 sensor was bad, so I bought direct fit replacement: WALKER Part # 25025001, which listed the 92 -95 VX and 92 - 01 HX as valid vehicles for this part number. I replaced the sensor yesterday (correct plug, no splicing anything), and the CEL came on w/ the primary O2 sensor code (61) after 10 miles. I figured I should have reset the ECU, so I disconnected the negative battery cable, waited a couple of minutes, and reconnected it. The CEL came on again about 50 miles later.

Any suggestions about what the problem is? Should I have bought the genuine Honda O2 sensor? There was no CEL before replacing this except a few times in the last couple of years as described in the thread mentioned above. Any suggestions is appreciated.

disconnecting the battery will not reset the ecu. the car is obd2 it has too be resetted with a scan tool.

Check the exhaust manifold for hair-line cracks, this is a well know problem with 1996-2000 Civics and will definetly set off the CEL.

** Update **

Found out from the auto parts store where I purchased the Walker O2 sensor that they had a bad batch of these with 80% of them returned. Not sure if it was only this specific Walker part number or all Walkers. I returned it for a full refund and purchased a $99 unit that someone recommended on another thread. No CEL.

Reallyslow: I've posted many times (and seen other posts) about resetting the HX ecu by disconnecting the negative battery cable and no one has ever mentioned that a scan tool is necessary to do this. Can anyone else verify this? Do I need to reset the ecu after installing the new O2 sensor 6 weeks ago, or does the ecu adapt to the new O2 sensor on its own?

You must use the scan tool to clear the code.

If you install a new O2 sensor, you will still have the CEL when you turn the car on.

I found this out with my 98 Civic EX.