CEL code 1 (02 sensor) .. your opinion?

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RHDism

Right Hand Drive guru
Throwing this one out there... feel free to throw your 2 cents in.

This is a 97 DX civic. D16y7 5speed OBD2a. stock

Throwing CEL code 1. This is trouble with primary 02 sensor.
(Tried swapping with known good 02 sensor and same trouble code.)
(Checked continutiy from the o2 sensor terminal to the ecu,. Good)

Typically an ECU will throw an 02 sensor code after then engine has started
and approaching normal operating temperature. If fault is present at this point
the trouble code appears.

In this situation, even after the ECU is reset and prior to starting the engine this code is present immediately after the ignition is switched to the on position.

What are your thoughts Hondaswap pers? :cool:
 
You checked continuity on a four wires? I know two are constant power but how'd you check the other two?
 
I will try and track down a 3rd "known good " 02 sensor, although given the symptoms and situation it seems unlikely.

Continuity was verified from the receiving end of the 02 sensor 4pin plug.

solid white, black w white, green with black and black with yellow which is igntion source power, not consant. None of them should ever be constant.
That would cause a drain.

I appreciate the responses, keep them coming.
I will report back. ;)
 
I meant a constant power when the key is in the on position. I thought two were signals sent from the ECU and I just wondered how you actually checked for continuity with those??
 
I meant a constant power when the key is in the on position. I thought two were signals sent from the ECU and I just wondered how you actually checked for continuity with those??

Continuity and resistance can be checked on any lead, with it being a power source or not.

The black with yellow is ignition 12vdc. Green w black sensor ground, black with white heat element, and solid white 02 signal. I spent a couple hours verifying continuity and ohm resistance only to find everything correct and in tact..

Here was the problem. I was mis reading the flashing CEL code.
I had myself fooled a single long flash was code 1. When in fact, it is code 10. IAT
Go figure, it was hanging there unplugged. :mad:
 
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