P2A00 Code after HFC install. Need some input

jockeus

Hey guys, I don't post alot here, but am a frequent reader. It's an awesome forum with alot of helpful people. You guys have helped me alot in the past with all the good DIY's and helpful posts.
This time however I need some input on my situation.

I installed the Berk HFC's a while back, and one of the O2 sensors gave me trouble. It didn't want to come off the stock cat, which resulted in some abuse and damaged threads.
Since I didn't want to buy a new one, I tried to install it anyways, and it seemed like it worked.

After a while though I got CEL come on. Torque told me it was "P2A00 - Powertrain" "O2 sensor circuit range/performance bank1 sensor1".
To my understanding this indicates the precat sensor on the passenger side is at fault?

Anyhow, after I got the code I started monitoring voltages on the post-cat sensors, and noticed that the one with damaged threads (on passenger side) consistently had lower voltage readings than the other.

Yesterday I switched sides on the sensors just to see if the readings would change, which they did. I now have consistently lower voltages on driver side o2 sensor.

I haven't gotten the CEL again after the switch, but I guess it's just a matter of time.

A thing to note though is that I recently started hearing a sucking/blowing air noise when letting off the gas at 1500rpm. I've had the CEL for a couple weeks and I noticed this sound maybe 1-2 weeks ago, not sure if it was there from the start, don't think so.

What do you think is up?
Bad precat O2 sensor? Postcat? Vacuum leak?
According to the service manual the postcat sensor is not a possible cause.
Should I keep driving until I get the code again to see if it switches to bank 2?

I am extremely grateful for any input on this, if you need any more info please let me know. Thanks!

gomer_110

Check for air leaks from the maf sensor all the way to the O2 sensors. A bad O2 sensor will often cause more than just the P2A00 code.

iirc most people that have had this problem generally found an un-metered air leak somewhere which once fixed resolved the problem. Do a search to find more info.

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SouthArk370Z

If the site's search isn't working well for you, go to any of the big web search engines and add "site:the370z.com" to your search string. Eg, P2A00 site:the370z.com

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jockeus

Ok, but I still don't get why the voltage difference switched banks when I switched sides on the o2 sensors? Could it be a leak in the O2 sensor threads, since they are bad?

Thank you, I have been reading a couple other threads about this, I guess I was wondering if it could have to do with the postcat O2 sensor.


I will read up some more, and check for leaks. Thanks for your replies!

SouthArk370Z

Since the bad reading is following the sensor, I think you have diagnosed the problem - bad sensor. O2 sensors are pretty fragile and you probably damaged it when removing.

Leakage past the threads could be the cause. Put some PTFE on the threads and see if the reading comes up. Don't run like that for very long as PTFE can form poisonous gasses when it burns.


You are welcome.

You could possibly also have a bad post-cat sensor but I'd fix the pre-cat problem before worrying about it.

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jockeus

I think I was a little unclear, it was the postcat sensors I switched, and the readings followed. I haven't touched the precat sensors at all. I can't seem to find any readings in the torque app for those either.
Even though the error code doesn't have anything to do with the postcat sensor, I feel like it could be related anyway?

jockeus

Update:
I haven't been driving the car very much since I switched the O2 sensors, but a couple days ago the code came back while the engine was idling. It's just that the code was "P2A03 - Powertrain" "O2 sensor circuit range/performance bank2 sensor1" and not P2A00 like before the switch.

Does this mean that the fault is most likely to be the postcat O2 sensor? Or am I missing something here?


EDIT

I ordered a new post cat o2 sensor, hoping this will fix it.

Do I just clear the code with the torque app after I've put the new one in?

jockeus

So I think i solved it.

I changed the damaged postcat O2 sensor, and now I get better voltage readings, and knock on wood, the CEL has not come back on.

I guess there must have been a leak at the sensor threads.