Error code 0420?

Hi,

There should only be two converters that attach (on each side) to the manifold. See pic 1 below.

If you look at pic 2, it is an exploded view of the rest of the exhaust system. Are numbers 5 and 9 what you are thinking are converters? I realize they look like they could. However, they are simply exhaust tubes.

Let me know.

Joe

See pics below.

What are parts 5 and 9 in the second picture, they're being labeled as rear catalytic converters on other sites, and on Amazon when I'm going to look for prices on replacements, they bundle them all together so you get 4, calling them the bank 1 front and rear catalytic converters, and bank 2 front and rear catalytic converters, and other sites are calling them primary and secondary catalytic converters.

.

For example.

Somehow, I missed the last part of what you said, addressing part 5 and 9, are you sure they're just exhaust tubing, because they're being labeled everywhere else as rear or secondary catalytic converters.

Hi,

According to my manual, they are front exhaust tubes. You were asking about pic 2 above. I attached the legend to that pic below.

To the best of my knowledge, there are only two.

Let me know if this helps.

Joe

See pic below.

Yeah, I don't know, that doesn't seem to be right, are you sure it's for a 2011 Frontier 4.0? I added 2 more pics from the Nissan website, look at number 7 and 8 in pic 1, pic 2 shows what they are, they call it "converter and pipe" which I assume is short for "catalytic" converter and pipe, maybe your manual is shortening it even more and just calling it pipe, or doesn't account for the fact that they actually has a catalytic converter in it as well.

I clicked on the part itself and saw the other names include "front pipe" or "tube exhaust front", as well as "catalytic converter", I'm thinking because the part normally in that spot is called "front pipe" or "exhaust tube front" typically, but this one just happens to also have a catalytic converter in it as well, so it's 2 parts in 1 and can be called either or both. I attached a pic where it says it's other names.

Hi,

That makes sense to me. Are you planning to install it yourself?

Joe

Yes.

Mike,

I don't know if you need them, but I attached the directions below. If nothing other, it explains the easiest way to access it. LOL

Take care and if you have a chance, let me know how things turn out for you.

Joe

See pics below.

Awesome great thanks, and will do.

Sorry, I forgot to get back to you on how it went. I just went ahead and replaced the front converter only, and it seems to have fixed the issue. Also while I was at it I removed the back converter to make it easier to remove the front one, and while I was at it I looked inside it to see if it was indeed another converter like I thought, and if it also looked dirty, and it was indeed a converter, and the cells looked much cleaner than the cells in the front converter, so I think I won't have any issues with not replacing the rear one. The only problems I encountered were when removing the exhaust manifold cover the bolts were very tight and 2 out of the 3 of them snapped inside there holes, luckily, I managed to get 1 off without it snapping so it still has 1 to hold it on there snug enough. And the other problem was after several hours of driving it I started getting a pa200 error code, for faulty wiring in the front 02 sensor, which is the one on the converter i replaced, and I figured I might have pulled a little to hard on the connector without holding tight enough on the back piece due to it being difficult to getting both hands in there with one of them around on the back connector to squeeze the release flap while holding the back connector tight so the other hand could pull to unplug the front connector that's connected to the 02 sensor, I did feel a little something like that when I was doing it, like a slight give or pop, like one of the wires might have been pulled out of the back of the connector a little bit, so I wasn't too surprised when I got the code. But I got back in there yesterday to try and see if I could see if any of the wires looked to be pulled out at all, all that I could see was one of the rubber rings that go around the individual wires in the holes where they insert into the back of the connector was sticking out slightly more than the others, by like 1mm, so idk if that was it, it was very slight, but I did my best to push the rubber ring back in with my thumb nail, and also tried pushing all the wires back into the back of the connector the best I could with the limited access I had, again it's hard to get your hands in there, especially around the back side of the connector. But I've been driving it around all yesterday and today and haven't gotten the code again, so I think that might've taken care of the problem.

I take it back, the pa200 error code just came back up. So as soon as possible I'm going to try and unplug everything the harness connects to on that side of the engine so I can pull it up through the top and get a better look at it and see if I can push the wires in properly, or fix the ends of the wires somehow, perhaps one got dislodged from the pin that crimps onto it before you slide it into the connector.

Hi,

The P0200 is a generic code related to an injection circuit issue, but it isn't listed for this vehicle. Are there any other codes present?

Let me know.

Joe

Sorry I said pa200 but I meant p2a00, which is for bank 1 sensor 1 o2 sensor out of range, and it stuck in my head as bad wiring because that was the one of the causes that I thought it was, because I just replaced the o2 sensor, and because I felt that popping feel when I was disconnecting it like I said. But after looking back at the causes again I remember the other causes it mentioned such as a blown fuse in O2 sensor circuit, low or excessive fuel pressure, vacuum leak, or exhaust leaks. I know exhaust leaks would make sense since I just replaced the catalytic converter, but I tightened everything pretty well, but I'll try and see If its leaking exhaust somewhere, not sure how though, might just spray the joints with soapy water or something to see if I see bubbles, unless you have a better idea. I'll also check the fuses and fuel pressure and see if I can find any vacuum leaks. I'm actually thinking it might be a vacuum leak because I recently removed the intake manifold, so maybe I didn't replace one of the hoses securely enough, or one might've been old and started to crack, so I might check that first. If you have any suggestions let me know.

Hi,

That code is related to the A/F sensor (o2 sensor). Possible causes are a vacuum leak, the sensor itself, fuel pressure, or a fuel injector issue.

Have you been able to check for a vacuum leak?

Let me know. Also, let me know if the fuel pressure has been checked. If it hasn't here is a link that explains in general how it's done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Take care,

Joe

Hey, sorry it took me a while to reply, I hadn't gotten a chance to work on the truck till yesterday. I checked for vacuum leaks and couldn't find any. I tried to check my fuel pressure, but there is no easy access pressure port, the only way other than lowering the fuel tank and checking it at the fuel pump, which is in the fuel tank, is to disconnect the fuel line where it attaches to the fuel rail via a quick disconnect connection, however I'm having trouble with that. I know normally there is a ridge on the male tube that the prongs inside the female quick disconnect connector latches onto so that you need a quick disconnect tool to remove it. I have a set of those in different sizes, but none of them work because there seems to be a second ridge on the male pipe, right outside the edge of the female quick disconnect connector, preventing me from sliding the tool under or inside the female connecter to compress the prongs so that I can release the connector. At first I thought maybe that was the ridge that the prongs were supposed to be catching, and that I must have released it already and that the pipe is just snug in there and I just need to pull a little harder, but I didn't want to pull too hard and break the prong, plus when I pull it you can hear the prongs catching on a ridge inside it, and it wiggles pretty freely until it reaches its stop and stops solidly, making the clicking noise of the prongs catching on something that must be a second ridge, so it's not like I got it passed the ridge and it's just on the pipe snuggly. I've also tried wrapping the tool around the ridge but when I do that the tool isn't flush enough with the male pipe to get under the female connector, it's either flush with the pipe but before the ridge so the ridge stops it, or around the ridge so it's not flush and can't get inside the connector. I've tried with all the sizes of the tool and can't get any under there. I've also tried, as I've read others suggest, to push down on the connector while pushing up on the tool, so that the prongs aren't in a bind with the ridge inside when I try to get the tool in there, but that isn't working either. I provided a picture to kind of depict what I suspect the situation to be, and a video where you can see the ridge that's outside the connector, blocking me from getting the tool in there, as well as how I can wiggle it and the noise it makes when it catches on what I assume is a second ridge. Here's the link to the video if it's easier: https://youtube.com/shorts/CKNEn_609Z8. Also do you have instructions for testing the throttle body, or a wiring diagram and the proper ohms or voltages I should be getting for each of the wire connectors prongs, I'm having trouble finding the info for my throttle body.

Hi,

I believe there should only be one ridge. If, however, there are two, if you have the tool to remove it, you should be able to get it over the second ridge.

I attached a pic below of the Nissan tool used for this. Is this what you have?

Let me know.

Joe

See pic below.

Similar but mine are metal, I have several in different sizes, I attached a picture of one of them. Try as I might I can't get it under with the ridge in the way.

Hi,

The one I sent a pic of may be thinner. That is the only thing I can think of. It should come off, but like everything, nothing is ever easy. LOL

Do me a favor. Stop at your local parts store and see if they have something thinner that they lend out to people. If you can't get over the first ridge, that is the only solution I can think of.

Let me know.

Joe

So, I managed to find thinner plastic ones that managed to get under and be able to bend so that it could continue under despite the angle it was coming in at. I just had to pull it out a few times and rotate it to be able to depress all 4 prongs, because the slit in the tool was opened wider due to having to go around the bottom ridge, causing it to not depress one of the prongs. But I got it off and it did indeed have 2 ridges, I attached a picture. But I put it back on because I didn't want to proceed until I found the proper pressure specs I should be looking for on an 11 Frontier 4.0, I couldn't find anything on any 11 frontier, I tried looking in regular service manuals, but they didn't have that info, and I can't find any factory service manuals available. I know people are saying a generalized 40 at idle for most vehicles, some say 50, and then different pressures when running, but I want to know for sure. Do you know what pressures I should be looking for when idle/running/off for an 11 frontier and how fast it should take to build or lose pressure, and/or the procedure for checking the fuel pressure the 11 frontier.

Hi,

I'm glad to hear you got it apart. Anything to make things a bit more difficult.

As far as the manufacturer's pressure specifications are concerned, at idle it should be 51 PSI. See pic below.

Let me know if this helps.

Take care,

Joe

See pic below.

Okay, so I tested it, at idle it's 47-48, after shutting it off after 15 minutes it's at 43-44, after 30 minutes it's at 37-38. Idk if the 47-48 is still within the normal idle range, and from what I've read if the pressure has gone down all the way within 15-30 minutes I probably have a leak, idk if that's just for a bad leak, and if mine is still going down faster than it should, or if that's about the normal rate it should go down. Also, I've been meaning to point out the symptoms I've been having in case it helps. It's been slightly sluggish accelerating, with a significant drop around 40mph when it's switching gears, which comes back up to the normal slightly sluggish around 45-50 MPH. Also, a very slight, barely noticeable, vibration at idle, that usually comes in waves. Lastly high rpms at startup, i think it's more intense when it has been sitting a while like overnight or a couple days, usually about 2,500 RPMs, sometimes 3,000 when it has been sitting longer, which quickly go down to 1,500ish within seconds, then gradually go back down to around 1,000 or slightly under withing a minute or 2. And I've read that high RPMs are normal if it's cold out, but I live in Florida so it's not cold out whatsoever, if anything it's hot. Idk if any of that helps.

Hi,

The manufacturer's pressure specifications are 51 psi. However, you are really close to that. If you clear the codes, what codes return?

Let me know.

Joe

So, up until now I've only been checking and noticing the p2a00 code come back after the check engine light comes back on after driving it for a couple days, but this time I decided to check randomly after like a day, before any check engine light lit up, and I got a P0420 code, which is said to be due to "catalyst system efficiency below threshold (Bank 1)" which is the side I just replaced the converter and upstream sensor on. After driving it another day or so that code disappeared and the p2a00 code reappeared along with the check engine light. I also got a p0603 code pretty much as soon as I cleared the codes I think, not sure if it was there before, apparently, it's due to PCM's Keep Alive Memory (KAM) self-test failing. But I think it's from me disconnecting the battery a few times when removing the fuel pump relay to release the fuel pressure before checking my fuel pressure a few times. That code also went away after driving it for like a day. So pretty sure/hoping that's all it was. So now I'm just wondering if the 02 sensor I installed shortly before replacing my converter is faulty. While driving I used a Bluetooth obdII scan tool to check out the voltage readings in comparison to the other banks 02 sensor and it's pretty erratic in comparison/ sometimes just way different, I attached some pics of the readings, the red lines are the problematic Bank 1 sensor, the green are bank 2. Can you tell just by those. Should I, or do you know how to, or is it possible to, test the 02 sensors pins with a multimeter to see if it's bad. Or do you have any other ideas what I should check before going down that avenue?

Hi,

It is operating within the specifications, and it is normal for it to jump around. However, if that was at idle and you weren't touching the throttle, it shouldn't do that. By chance, do you have an exhaust leak before the sensor? The P2A00 is for the air/fuel sensor (o2 sensor).

Also, the P2A00 code is unique because if the KAM is lost, so are the values of different sensors, including the air/fuel ratio. Battery voltage is supplied to the ECM even when the ignition switch is turned off for the ECM memory function of the DTC memory, the air-fuel ratio feedback compensation value memory, the idle air volume learning value memory, etc. I have a feeling that is why the code shows up and then goes away.

Take a look at this link and let me know if it helps:

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor

Let me know.

Joe

Sorry, I just noticed I was looking at the sensor 2(downstream) sensors, because how they had them labeled, I was expecting to be labeled like bank 1 sensor 1 and bank 2 sensor 1, with the bank displayed first but they had it has Sensor 1 bank 1 and sensor 1 bank 2, and I was reading fast and got it mixed up in my head. But the sensor 1's are actually really stable and even with each other, when Idle and when driving. But the sensor 2 readings are the ones that are very unstable. I couldn't remember which ones of the first ones I took where at idle so I took some more pics at idle and attached them, the first 4 are both the sensor 2's again, this time all at idle, after driving it around and letting them warm up a bit, the last 2 pics are of both the sensor 1's, in case you want to see those, I took them while driving because they were both just an identical flat line at idle, when driving there are only very marginal deviation from each other. But with the sensor 2's what's interesting is first how different they are, bank 1, the green line, the side with the error, stays relatively stable at little less than .05v, while bank 2, the red line, when stable, stays around .8v, way higher, the second interesting thing is that it's the bank 2 sensor that will occasionally drop drastically out of nowhere, just when idling, then shortly return back up to around .8v. So, I'm wondering if bank 2's maybe bad, and if that could cause back pressure to add pressure to bank 1's side or something to cause bank 1's sensor to be sensing a problem idk. The other thought is that since both sensor 1's are very stable and similar and it's the sensor 2's that are showing discrepancies, that seems to me like that might indicate an exhaust leak like you suggested, do you agree? I haven't gotten a chance to get in there and really check, a while ago when we first started looking into this, I just did a visual check and listened and felt for any exhaust coming out the catalyst joints/connection points, didn't get around to using soapy water to look for bubbles. But if that's the next likely suspect that will be the next thing I do. Also, I'm assuming if I can see the voltages of the sensors using the OBD scanner I shouldn't need to check the voltages of their data pins using a multimeter, correct?

Hi,

If sensor 2 is the one that is off, then either we have a leak, or the converter may have failed. Also, you have all the voltages listed above, so no need to use the meter.

Let me know if you find any leaks.

Joe