P2A00 code, HELP
 

Hey guys, I have a P2A00(A/F bank 1 performance) code. I replaced the sensor with a Denso sensor, cleared the code and the code came back 2 days later. Any ideas?

F.Y.I I bought the car with Stillen Cat backs and Stillen Gen 3 intakes on it already

You are running two different branded O2 sensors?

no test pipes/hfc's?

There's a lot of info on this code. Exhaust leak and dirty MAF's seem to be the top two problems. There's more that can cause it.

Have you confirmed this.

note the question mark- I was asking the OP.

No test pipes or hfc and I just replaced the stock o2 with a Denso o2 on the passanger side

I know that smart guy. Im confirming this with the op to make sure he has looked. Don't flatter yourself.

Aftermarket sensors may read differently from the stock ones. If you are running mismatched O2 sensors, it is very possible and likely to throw a code because your ECU is seeing a voltage variance. I would either replace your other O2 sensor with a Denso, or replace the Denso with a stock one. Just make sure they match.

Ok, tommorow at my shop I will use the scan tool to read voltages of both o2 sensors and get back to you guys I will also clean my MAF sensor. Thanks for the feedback to this point

Checked with my scan tool found bank 1 fuel percentages at 22 and bank 2 fuel percentages at 7 thinkong I need a MAF in bank 1 so I'm swaping sensors and rechecking

Stupid question, but have you cleaned the MAFs yet? It's far cheaper than the alternatives.

I think he means he is going to swap them and retest to see if that confirms a bad or dirty MAF.

Might as well hit them with maf cleaner while they're out. Can't hurt.

This exactly is what I did and I powered down all ECM components by removing and toucing battery positive and negative cable. All my reads look good as of roght now we will see after I drive 50miles or so

This exactly is what I did and I powered down all ECM components by removing and toucing battery positive and negative cable. All my readings look good as of right now we will see after I drive 50miles or so. Hopefully the problem moves to bank 2 and I can just clean the sensor

Not a good idea. It can cause surges/spikes in the system that can kill components. It's cumulative damage, so you can probably get away with doing it that way for a while, but it will eventually bite you.

Instead of shorting the terminals, use a fairly large resistor - 1-10 megohms and ~1 Watt (I'm not sure how much energy the system retains, so 0.25-0.5 W may be big enough). This will allow the system to discharge over a few seconds and avoid the spikes. You can avoid sparks around the battery by placing the resistor between any "always hot" point and ground.

Edit: Or, as others have mentioned, step on the brake. Much easier than using a resistor and accomplishes the same thing. ;)

What's wrong with disconnecting the battery and holding the brake pedal for a bit?

Nothing. This is what most people do to discharge the battery.

Ok well good and bad news. Code stayed off long enough for me to get it through inspection but came back today. My short term fuel trim for bank 2 is at 22percent my short term fuel trim for bank 1 is 3percent....MAF is reading 3.6g/s. Any ideas?

I still think those mismatched sensors might be doing it. Expensive endeavor to replace though.

So you think go with a factory a/f sensor? I can return the Denso one w.o any problems.

It would definitely be the route I would go. You can sometimes find oem ones cheap on ebay, look around first before ordering one at full price.

Do you know what brand O2 is stock?

I just searched for an oem precat passenger or driver side of my model year. I was lucky as hell to find one on Ebay for like $50... Don't expect to find it that cheap though.

Old thread showing a few places where to buy.

http://www.the370z.com/intake-exhaus...n-sensors.html

Ok, well that thread actually states that the stock sensor is a Denso. Which is what I put in. So I'm back to square one. Is there an AirFuel mixture relearn?

Can't find a consistent part number to verify or manufacturer of the part. But this is from 3 companies selling new or used sensors and three drastically different price points :/ Not sure what to recommend or if your Denso is fine at this point.

OEM 2011+ VQ37VHR Front Oxygen (O2) Sensor

11 Nissan 370Z Exhaust Manifold Oxygen Sensor R18883

AIR FUEL RATIO SENSOR - 370Z (Z34) 2009+ :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com

Any updates? I want to go this set up but don’t want to deal with a cell. I have heard so many people with just Stillen G3’s and CBE and getting a cell. Per their website it also states on the G2 description No Check Engine Light (CEL) Problems. But on the G3 description states nothing about a cell which intern means they are aware it can cause a cell. Anyways bro you have already determined it’s not the 02 sensors. Did you end up cleaning the Maf sensors?

I would get a matched set of O2 sensors. There may be an electrical issue such as a higher draw on one versus the other or mismatched resistance which is causing the issue.

Cleaned them light came back on after 50 miles

The stock sensor is a denso. I got a denso sensor.

I know of some people that have had either a clogged air filter, intake leak after the MAF or an exhaust leak. Also I would consider looking into the electrical connection at the connectors between wire harness and sensors on that side. Check for broken of crimped wires or prongs inside the plugs themselves.

Did the fuel trims change banks when you swapped the sensors?

Edit- read more carefully. The discrepancy is still on the same side. Time to look for vacuum leaks, etc.

Ok to update still ahve the code cant find any problems at all. ONce the weather got cold i retrieved a P0300 code multi random misfire. Usally a Lean miss fire so im asuming im getting a lean miss which is caused by a vacuum leak between the A/F bank 1 sensor 1 and the MAF sensor?

Reviving this old thread. I finally got rid of this code once I installed high flow cats. To the guys running stock cats (but have other breather mods), you might want to consider an option that extends the 02 sensor out.

They didnt delete the code is just went away on its own?

I had this code and my mechanic found a crack in my catalytic converter. He welded it up and the code went away. He explained that if there's a difference in the O2 sensors, then the code will be triggered. Since the crack let in fresh air, then there was a mismatch between the sensors, therefore the code was on.

I just posted a comment about the PA200 code on another member's post that I was receiving. Through the process of elimination, I found out it was the gas (Royal Farms') I was using.