97 Honda Civic DX O2 Sensor

I have a 97 Honda Civic Manual transmission and my Check Engine Light Came On. The error code is P0135 which shows up as needing a O2 sensor. My question is:

#1. Do I need to replace it?
#2. How long do I have to replace it?
#3. Will driving with it as it hurt my car?

I live in Wisconsin and the weather is getting colder and I read that could be the cause. I really don’t have much extra money but I don’t want to kill the car. I have kept up on Oil Changes with MaxLife Full Synthetic, Radiator Flush, etc if that matters. I also went into Valoviline Instant Oil Change and they double checked all of the fluid levels and that was OK.

Taint necessarily the sensor.
It could be wiring, blown fuse or corroded connector.
The sensor can be tested with an ohmmeter.
The cat converter might be damaged. Gas mileage will suffer.
With the light on another problem might crop up and you won’t know it.

MAF sensor, bad air filter, How old are the plugs? Maybe some sea foam would help, I feel like a blind guy in a black box trying to guide someone to the light.

Your code is for the heater circuit in the O2 sensor. Once the sensor heats up from the exhaust gasses, it will work like normal, the heater circuit is just to get it working a little sooner. It could be a connector but most likely it is the heater in the sensor itself.

circuiysmith — "The sensor can be tested with an ohmmeter."
Only the heater circuit can be tested by an ohmmeter.

Only the heater circuit needs to be tested.

circuiysmith — "Only the heater circuit needs to be tested."
Not true. The heater only performs its function for the first 2-4 minutes. After that time it is essentially out of the circuit. That is why are always two DTCs for O2 sensors: one for the principal circuit, the other for the heater circuit.

The principal circuit acts as a battery when the concentration of O2 ions is greater on one side of a ceramic body than on the other. If the ceramic body is fouled by leaded gas or by HC deposits, the sensor output voltage will not reflect the distortional concentration of O2 ions between the exhaust stream and surrounding air.

The DTC was for the heater circuit, so I told the OP how to test the heater circuit.
Was the long explanation about “O2 ions” for me?
You wasted your time because I already know that stuff.
And the O2 MOLECULES aren’t necessarily ionized.

circuitsmith — "Was the long explanation about "O2 ions" for me? You wasted your time because I already know that stuff." And the O2 MOLECULES aren't necessarily ionized."
Only ionized oxygen atoms matter in the operation of an O2 sensor. In any quantity of air a small percentage consists of ionized oxygen atoms. They carry a charge which they deposit on the air side of the O2 sensor. When the exhaust side of the O2 sensor is HC rich, there are few ionized oxygen atoms (or any O2 molecules, for that matter) on the exhaust side. The accumulation of ionized oxygen atoms on the air side and the absence of ionized oxygen atoms on the exhaust side is the cause of the ≈1 V potential difference across the sensor when the exhaust is running rich. If natural air did not contain a small quantity of ionized oxygen, the operation of an O2 sensor would be impossible.

I say REPLACE THE O2 and see what you get…NO…BETTER YET…if you want you can pull the one you have…clean it off re-install…clear your codes…you can pull the pos term of the batt…see if you get the same codes again and if you do…then replace it… If you get the code after that…its a wire thang…and we can cross that bridge when you get to it

HB, that wont work in his case, its not the sensor itself that isn’t working. The computer is not detecting the correct amount of current flow through the heater circuit of the sensor when the engine is cold. It’s just fundamental resistance heating.

Same code on my 1996 Civic HX - I replaced the downstream sensor (there were 2) and the code disapperaed. The sensor had been there since '96 I’m guessing so heating up the engine alittle and using lots of lubricating oil helped but it was still tough to get out which is why new )2 sensors come already graesed.