What does the Faulty A/F sensor 1 mean?

[autoq]

97 Honda Accord LX 4 cyl. auto engine light is on. I have it scanned by the AutoZone. The Troubleshooting is PO135. The Definition is sensor 1 heater system malfunction. Problem cause 1.- Open or short circuit condition; 2.- Poor Electrical Connection and 3.- Faulty A/F sensor 1.

What is the A/F sensor 1? Does it mean front, back or both sensors? Can you explain it? Thank you.

[somick]

I am pretty sure this is your oxygen sensor.

I believe there is testing procedure for it. May be in Haynes manual.

You may also check www.tegger.com. There is a lot of information there.

Goog luck,
Sam

[autoq]

Originally Posted by somick

I am pretty sure this is your oxygen sensor.

I believe there is testing procedure for it. May be in Haynes manual.

You may also check www.tegger.com. There is a lot of information there.

Goog luck,
Sam

If A/F sensors 1 mean oxygen sensor, can you or anyone tell it is the front or back sensor?

[jeffcoslacker]

Sensor 1 is the pre-cat o2 sensor, the fault is saying the preheat grid for it is reading as open circuit. This will prevent the sensor from working right until the motor is pretty warmed up. But all it should affect is cold-start emissions. I doubt it would change how it runs. You probably need to replace that sensor, or make sure it's wiring isn't laying on something hot and burned up or something.

I'm not sure how a faulty airflow sensor might figure into it, I'd check/test the o2 sensor first. If you can find a reference that tells which wire is which, I'd start by checking for continuity across the heater grid leads. If it reads infinite, the element is likely shot.

[autoq]

Do you know where is the Sensor 1, the pre-cat o2 sensor? I was told there are two oxygen sensors on the 97 Honda Accord LX. One is in front which is easy to be replaced while another is in back and the car must be lifted for the replacement of the back oxygen sensor. I do not know the A/F sensor is the front or back oxygen sensor. Does anyone know it?

[jgr7]

I have a PO141 which is bank 1 sensor 2. This is the sensor after the cat I was told so I would say bank 1 sensor 1 is the one before the cat. Do a google search of your code and you should be able to find more info. Also it is recommended to use Honda sensors instead of after market as there seems to be a lot of return problems with the quality control of after market parts leading to another replacement of same part. The O2 sensor for my 96 Accord V6 is $300 out the door. I have mine sitting on the counter right now and will be changing it this weekend when I change the oil then going for a smog inspection.
Jeff

[jeffcoslacker]

Sensor 1 is always the pre cat o2 sensor. This is NOT the AF sensor, that is on the intake side of the motor, tells it volume of air being delivered to it.

That's why I said I don't think that code is correct...it may be just throwing that out there as a possibility, in case the AF is sucking air or something, that would make the PCM's mixture calculation wrong, which would cause abnormal conditions in the exhaust coming out of the motor, and that could set a code for the pre cat o2 sensor, if it believed the reading was not legit...but the o2 sensor code you have is for a malfunction in the heating grid circuit, not it's actual exhaust reading...so I think the two are not related...you might just be dealing with an old code that is a red herring too...might be meaningless. Did AZ turn the light out and these codes came back, or not?