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Did I replace the wrong O2 Sensor?

2004 Honda Civic with 166000 miles.

–Had Check Engine light on for a couple days and code reader said P0135. Parts guy said this means “Bank 1”, my Haynes book calls this code for " Primary Sensor 1" Is this the same as “Upstream”?

–Replaced O2 sensor (Denso 192400-1160 05F12) myself with a new one (Bosch 15710). Fit perfectly, plugged right in.

–Check engine light goes off for about 5 minutes but comes back on with code P0134.

What should I do now? I replaced the sensor closer to the engine before the catalytic converter. Very easy to reach from the top. I rented the correct tools and did not damage or force anything. Is there a second O2 sensor after the cat that is not so easy to reach? Was that the one I needed to replace? Did I misunderstand the meaning of “upstream” or “Bank 1”?

Thank you for your help in advance.

The sensor you replaced provides the signal to the ECU for proper fuel metering. There is a second one after (“downstream from”) the cat converter that monitors the performance of the converter and trips the code you’re seeing of it detects poor catalyst performance.

“Bank one” is basically the only one you have, since Civics only have inline 4 cylinders. “Bank 2” is used for systems that have V6 engine, like those available on the Accords.

You either need to replace the downstream sensor or replace the catalytic converter. I’d try the sensor first, clear the code, and see if it reoccurs. If not, you’ve won the bet. If it does, you’ve lost nothing, as you’d want to replace the downstream sensor when you changed the converter anyway.

P0134, A/F sensor (upstream) no activity. Unplug the connector and inspect for loose pins/connectors.

Either a air/fuel ratio sensor is used or a oxygen sensor depending on which engine your car has. You may have install the wrong part for the application.

Damn, damn, damn. Now I have to pull my foot out of my mouth yet again. I thought my memory was better than that. I KNEW I should look up the code before posting.

Thanks for the correction, Nevada. Someday…maybe…if I live long enough…I’ll learn not to trust my memory.

You had 420 on your mind.

You may have installed a defective O2 sensor. It’s happened to me a couple of times.


Or you bent a pin in the connector when you plugged it in.

Thanks for your help everyone. I am hoping it is a defective sensor. The pins are well-protected by the wiring harness plug and I don’t think they could be bent, but I’ll take a look. I did coat them with dielectric grease beforehand.

What are the chances that the wiring harness itself is bad? I am guessing not by the fact that the new sensor worked for about 5 minutes/2 miles.

“Replaced O2 sensor (Denso 192400-1160 05F12) myself with a new one (Bosch 15710)”

Some of these systems are very picky.
You might need to get another Denso.

I’m with @circuitsmith. I’ve had no luck with aftermarket O2 sensors.

From the Rock auto catalog the Bosch #15710 ($22) is an oxygen sensor for a 1.7 L CNG civic.

A wideband air/fuel sensor for a 2004 civic1.7 L SOHC is #13705 ($122) or #15473 ($188) , note the different wire length.

An oxygen sensor can’t be used in place of a air/fuel ratio sensor.

Dielectric grease is an insulator. Clean out the interior of the plug with alcohol (91% min) and a Q-tip and reconnect.

OOPS! I misunderstood the use of the grease.

Anyway, Circuitsmith was right–I did need another Denso sensor. I tried 2 identical Bosch ones, each lasted about 2 minutes before setting code P0134.

Bosch website, Pep Boys website, and Pep Boys internal database all recommend the Bosch for this vehicle! How is this not fraud?!? Luckily they did allow me to exchange the bad ones.

Problem solved! Thanks CarTalk Guys esp. Circuitsmith!