P0420 pending?

Good evening
I've made posts before about certain codes I've expireanced and asked for advice. Well now I have one that doesn't seem too straight forward to me once again. My truck seemed to throw every code at me in the matter of 2 weeks early this year so now I'm on the final leg of getting it up to snuff. This last one has been the death of me. I had to infamous P0420 code and I know how finiky this code it. Originally tried to cheap our, get a cheap set of cats and thought that would solve my issue... nope. They weren't even functioning, learning from my mistakes on cheap stuff. I have a local shop that specializes in Toyotas and Japanese cars and they tested the code (I have replaced the 02 sensors, gas cap, and the cheap cats at the time with a new oem muffler that took a dump on me too just like the one I got Originally with the truck) and they told me the 02 sensors worked perfectly, however the cats were junk and not functioning. Fine, I skimped on that and will admit it. Plus i was quoted a arm and a leg from this shop and same with oem from Toyota. Being mechanically included myself with a lift I tackled the new cats myself and went out and got magnaflow cars designed for the truck (at least it was listed specially for 2003 4x4 2.7 tacomas anyways on their site) installed them, cut off the factory muffler and put on a flowmaster FX series and it really woke my old 4 banger up. It feels much happier and no engine code since. So why this post? I went today to get a E-check here at my county in Ohio and somehow my truck failed. Guy told me the codes for the Cats are still in the system and I need to drive the truck around more to let it work in. OK fair enough, but I decided to hook my code reader up to my truck and there is a P0420 (Pending) code that keeps popping up. Usually I would have a check engine light pop on when I'd get the regular code but never had the pending before. I just installed the cat and exhaust about 2 days ago now and I thought it would've worked outta the system by now. Can I get anyone's advice as to why this is happening? I have no check engine light, every exhaust gasket is brand new, 02 sensors are factory Denso oem sensors, muffler is a high flow muffler with no restriction, and the cats are magnaflow federal grade oem compliant for my year... any advice would be much appreciated as to why I have the pending code and how to work that outta the system. Thanks a bunch.

 

Do you have a cracked exhaust manifold?

 

How would I be able to tell that? I don't have any noise like a exhaust leak but I have not checked

 

And if it was that would that be a pending code or would that set my check engine light off again?

 

On my 2.7 I can see a hairline crack down the exhaust manifold through the heat shield. Don’t know why yours is still pending but I have heard of people with cracked manifolds having P0420 codes.. including myself. Just throwing that out there could be completely wrong but it seems like you have tackled all other culprits.

 

You can see it through the heat shield? Ok I will be looking that over in the morning to see. That seems like the frontrunner as of right now but like you said the pending is weird. I know a service manager at Toyota and he told me that due to me just clearing the code in the system that it has to reset itself by driving it around a bunch to let it work back in, does that seem like bs or a possibility? Thank you for you advice so far, much appreciated.
Matt

 

I just read another forum where my 2003 has the improved design and not the cast one that cracks! Bummer, kinda rules that out

 

Still worth a check all manifolds can crack. Also disconnect the negative and positive battery cables and touch them together, this will drain any power to the ecu and should help your truck start over if the cats were the problem this might clear the pending.

 

Ok will do, the thread I read said in the last year's of the 1st gen they went to the steel header design and that they don't crack but I will still inspect in the morning, as you have said there isn't much more that could be done. I will try disconnecting the battery and letting it sit with it off for a bit too.

 

Check for vacuum leaks, I have had a vacuum leak throw me this code on my 2.7.

 

There is a specific drive cycle that needs to be performed for the pending code to clear out after you’ve cleared the regular code.

someone posted the PDF on here a while back, I can’t remember who.

It is something like a full warm up, then a drive with several ranges of speeds like 5 minutes at 20min, then 10 min on freeway or something.

 

Great, this a good start for me tomorrow to look at. I appreciate the advice gentlemen. Much appreciated
Matt

 

Wow I just looked up and I think I found the drive cycle procedure. How finicky are these toyotas???? Plus they said I have to be between 3/4 and 1/4 of a tank!! How strange! Very specific things mentioned on that!!

https://www.tacomaworld.com/threads/03-tacoma-drive-cycle.606296/

Here is the link I found, good thing I have a day off tomorrow! Sounds like I'll be putting some miles on the old girl!
This may sound bad but if I disconnected the battery would I be able to skip all this crap?

 

No, if anything you would make the pending code take longer to go away.

 

Ok thank you, much appreciated, would that also explain why I don't have a engine light but just a pending code?

 

Confirm you don’t have any exhaust leaks. A small leak between the rear cat and o2 sensor was my problem. Chris fix has a good video on how to find exhaust leaks.

 

What code reader do you have and is it capable of displaying live data, specifically O2 sensor voltage readings?

 

Just redid the entire exhaust system 3 days ago now. All new seals that I went through and made sure were sealed up

 

Yes I do have a code reader that can display live data, what should I look for?

 

How did you confirm the seals were good/no leaks?