Need Help O2 sensor check engine
 

Hello all:

I had the check engine light come on my 2004 Civic EX. Hooked it up to code reader - said PO135. Replaced the front O2 sensor primary.

Cleared out check engine light. Drove good for 10 miles no light.

Now the light came back - says code PO134 - no activity Bank 1/sensor 1 (same sensor)


I checked harness looks good...any other ideas? I went with a NTK(NGK) O2 sensor plug and play no splicing.

This has been driving me crazy...:mad:

Thanks!
Ryan

Check the O2 sensor heater element for resistance and short to ground. The resistance should be 10-40 Ohms. Also check the wires for an intermittent short or open and inspect the connector terminals.

Drove me crazy too. I traced the CEL code and pulled the sensor and found open circuit on the heat element on the primary sensor (upper, upstream of the cat converter) and went the cheap route and bought a $68.00 universal sensor from Advanced Auto. After the replacement and an ECU reset, the CEL light stayed dark for about 10 miles when the engine started surging and the CEL returned. I have no problem with Advanced Auto and I will buy there in the future, but the 'universal sensor' was probably a narrow band 0-1 volt sensor. It didn't work. I went nuts tracing and testing to track the problem (meanwhile state fines for emissions inspection failure increased). As you might imagine, I have problems paying dealership prices. Turns out that paying $181.00 (Annapolis MD Honda parts counter quoted $225.00 but 'none in stock') to Autopartswarehouse.com for part # 234-9005 finally solved the problem. I'm not a shill for any company. I was going nuts tracing and trying fix my CEL/inspection emissions failure. Honda Civic Forums helped me and I hope I can help others. Here are some numbers on the O2 sensor for this 2004 Civic LX: Original Sensor was Denso DU2 192400-1160 08E-26. Numbers on the sensor that worked: Denso 192400-8040 U2M08. I suspect that the original and replacement sensor are wide band 0-5v sensors and am curious. I will set up a 600* propane torch and measure voltage outputs and post again.