P0421 Warm Up Catalst Efficiency Below Threshold Bank 1

[mcanedo92588]

So I just got this code today after filling up with gas. I have been having an oil consumption issue where my car burns oil pretty much every time I start it in the morning after it has set all night so maybe this helped cause the issue. I have read a few threads where pretty much because my car has no symptoms, it is just saying that the emissions are above normal and my catalytic converter could be on the way out. I some questions to anyone who has prior knowledge on this. I was looking at ECS and of course a genuine remanufactured catalytic converter is about $1300 while a Magnaflow one is only like $250. So what are my options...?

Here are my questions:
1. If it gets worse, will I notice right away and how bad will it actually get?
2. I don't really want to just do the temporary fix with the spacer in the o2 sensor, what is my best route not going OEM and spending thousands?
3. Can I really just get the Magnaflow one and be good? I have Magnaflow 14851, should I pair those with something special to make them still sound good/better and fix my problem?
4. Anything I need to know/check about this issue, in college and just paid tuition so I am flat broke ATM, looking for my best alternative to fixing the problem without breaking the bank.

[customa4]

What engine, 4.2?

[mcanedo92588]

What engine, 4.2?

3.0

[cschuster]

Pretty common code for the 3.0. The cat not performing like the ECU thinks it should. I just clear mine when it comes up, been doing that for a few years. I probably burn a quart every 10k miles with 112k on the clock.

No emissions laws in KY so I don't really care about spending the time/money to replace it, but your state may be different. If so, an aftermarket cat will be just fine. No need to add anything else unless you want to.

[mcanedo92588]

Pretty common code for the 3.0. The cat not performing like the ECU thinks it should. I just clear mine when it comes up, been doing that for a few years. I probably burn a quart every 10k miles.

No emissions laws in KY so I don't really care about spending the time/money to replace it, but your state may be different. If so, an aftermarket cat will be just fine. No need to add anything else unless you want to.

Yeah, I have some weird consumption problem Audi couldn't even diagnose. I go through about 1.5 quarts every 1000-1200 miles, pretty ridiculous but it doesn't seem to be causing any problems or whatever, no leaks that are noticeable so everyone I have had look at it is baffled. I am just wondering what my best options are for getting it replaced, should I just get the magnaflow 2.25 inch one and be done with it? Also what is the bank 1 mean, is that just 1 of them is going, I am assuming drivers side or left would be bank 1 correct? Anyone with some more knowledge than me, please let me know what I am looking at here. Thanks!

[old guy]

Bank 1 is the side with cylinder #1. On the 3.0 that would be the riders side. If you don't find and fix the high oil consumption you will go through a new cat rather quickly.

[mcanedo92588]

Bank 1 is the side with cylinder #1. On the 3.0 that would be the riders side. If you don't find and fix the high oil consumption you will go through a new cat rather quickly.

What else is there that I can do/check? I have already spent hundreds having several mechanics check out the problem, even the dealership cannot find the issue. They told me it would be cheaper/easier just to keep adding oil every month or so rather than paying more for even more in depth expensive tests. Not even sure everything they all did, but I am pretty sure without taking half my car apart they said there is nothing else they can do for me.

[old guy]

Do you know if they checked out the block breathers (PCV) system?

[SJorge3442]

Don't replace it with factory cats. Use jhm down pipes. Cheaper and they actually add performance. Also the jhm ecu tune will remove the cat efficiency codes

Sent from my HTC One using Tapatalk

[mcanedo92588]

Do you know if they checked out the block breathers (PCV) system?

Yep, that is one of the first things the dealership did for me.

[diagnosticator]

Yeah, I have some weird consumption problem Audi couldn't even diagnose. I go through about 1.5 quarts every 1000-1200 miles, pretty ridiculous but it doesn't seem to be causing any problems or whatever, no leaks that are noticeable so everyone I have had look at it is baffled. I am just wondering what my best options are for getting it replaced, should I just get the magnaflow 2.25 inch one and be done with it? Also what is the bank 1 mean, is that just 1 of them is going, I am assuming drivers side or left would be bank 1 correct? Anyone with some more knowledge than me, please let me know what I am looking at here. Thanks!

The oil consumption symptoms you described are most likely caused by worn-out age and heat stiffened valve stem/guide seals. The valve stem seals can be replaced without removing the cylinder heads, and will reduce the oil consumption to normal and stop the smoking. Like Old Guy said, you should address the high oil use at the same time the cat is replaced. The Magnaflow cat should do the job, but won't be as effective and the OEM cat, because the aftermarket cats don't use as much catalyst platinum and iridium metals on the cat matrix core compared to the much more expensive OEM cat.

[mcanedo92588]

Don't replace it with factory cats. Use jhm down pipes. Cheaper and they actually add performance. Also the jhm ecu tune will remove the cat efficiency codes

Sent from my HTC One using Tapatalk

I never really have looked in to an ecu tune, don't I have to pull my ecu to do that, doesn't that mean I can't drive my car while I wait?

[mcanedo92588]

The oil consumption symptoms you described are most likely caused by worn-out age and heat stiffened valve stem/guide seals. The valve stem seals can be replaces without removing the heads, and will reduce the oil consumption and smoking to nearly new engine rate. Like Old Guy said, you should address the high oil use at the same time the cat is replaced.

You would figure that Audi would have looked at that when trying to figure out the oil consumption issue right?

[mcanedo92588]

I am thinking about just doing this for the cat for starters, any thoughts? Looking to just get it done fast and cheap but still decent.

http://www.ebay.com/itm/321350216074...84.m1423.l2649

[diagnosticator]

You would figure that Audi would have looked at that when trying to figure out the oil consumption issue right?

There is really no test that can say for sure that the valve stem seals are age stiffened and are leaking oil or not. Technicians with less experience often don't think of the valve stem seals. It's generally a simple matter of age and mileage, and experience with other engines with similar symptoms. In your case, since the engine runs fine otherwise, that implies the piston rings are not causing the high oil consumption. Therefore, the only other likely cause is leaking valve stem seals. (provided the oil is not leaking out of the engine some place else,) Bad valve stem seals will allow oil to be sucked into the intake ports when the intake absolute pressure is low, with closed throttle angles, and then burned causing the blue smoke at startup, that goes away as the parts warm up from expansion with heat, although oil still leaks past the seals after warm up. Leaking exhaust valve stem seals will allow exhaust to leak into the crankcase, adding to the blow-by gasses that must be ventilated from the engine, in extreme cases, the excess crankcase pressure will provoke oil leaks from the engine, in addition to oil being burned. When the symptoms indicate the valve stem seals are most likely the cause for excessive oil consumption, without other symptoms like low compression, or rough running hard starting, etc. I have had success reducing oil use to > = < normal after replacing the valve stem seals. I have not once been disappointed with the results. This depends on accurate evaluation of the condition of the various engine parts involve with lube oil consumption before replacing the seals.

[imnuts]

You might get rid of the code with non-OEM cats, but odds are, the code isn't going to go away for very long. If you don't want to do the ECU tune, you could get O2 sensor spacers for the rear sensor, which would fool the ECU. I'd second the PCV being the issue on oil consumption. Do you know if they changed everything, hoses and valve? Or did they just change the valve itself? If they didn't change it all out, the piping could still be clogged, keeping a new valve from working properly.

[mcanedo92588]

You might get rid of the code with non-OEM cats, but odds are, the code isn't going to go away for very long. If you don't want to do the ECU tune, you could get O2 sensor spacers for the rear sensor, which would fool the ECU. I'd second the PCV being the issue on oil consumption. Do you know if they changed everything, hoses and valve? Or did they just change the valve itself? If they didn't change it all out, the piping could still be clogged, keeping a new valve from working properly.

Not sure what you are referring to, sorry. Originally I had a slightly oil problem back in like July but it wasn't terrible. I had the valve cover gaskets replaced a few months ago (maybe 3-4) and at the same time he did the spark plugs also. The guy said the spark plugs looked clean which meant the heads were fine because the oil wasn't coming through or something like that (sorry for my ignorance, I am new to all this DIY stuff). I had the dealership check the PCV and crankcase and whatever else they could get their hands on within the hour. Have yet to do anything about the cat, still looking at my best options without spending thousands on something that isn't even a terrible problem atm.

[mcanedo92588]

There is really no test that can say for sure that the valve stem seals are age stiffened and are leaking oil or not. Technicians with less experience often don't think of the valve stem seals. It's generally a simple matter of age and mileage, and experience with other engines with similar symptoms. In your case, since the engine runs fine otherwise, that implies the piston rings are not causing the high oil consumption. Therefore, the only other likely cause is leaking valve stem seals. (provided the oil is not leaking out of the engine some place else,) Bad valve stem seals will allow oil to be sucked into the intake manifold and then burned causing the blue smoke at startup, that goes away as the parts warm up from expansion with heat, although oil still leaks past the seals after warm up. Leaking exhaust valve stem seals will allow exhaust to leak into the crankcase, adding to the blow-by gasses that must be ventilated from the engine, in extreme cases, the excess crankcase pressure will provoke oil leaks from the engine, in addition to oil being burned. When the symptoms indicate the valve stem seals are most likely the cause for excessive oil consumption, without other symptoms like low compression, or rough running hard starting, etc. I have had success reducing oil use to > = < normal after replacing the valve stem seals. I have not once been disappointed with the results. This depends on accurate evaluation of the condition of the various engine parts involve with lube oil consumption before replacing the seals.

Sounds logical, how time consuming is the process of changing the valve stems? I usually get work done from my mechanic friend for about $25-30 an hour depending on the job and wondering how long it might take to figure out when I can schedule it. Also, I would need 30 of these correct?

[diagnosticator]

Sounds logical, how time consuming is the process of changing the valve stems? I usually get work done from my mechanic friend for about $25-30 an hour depending on the job and wondering how long it might take to figure out when I can schedule it. Also, I would need 30 of these correct?

Replacing the valve stem seal without removing the cylinder heads, is not difficult for someone with mechanical experience. Its a lot less work and expense than removing the heads.

The procedure is comprised of the following basic steps.

Position crankshaft at number 1 cylinder bottom dead center piston intake stoke.

Remove camshafts from the heads.

Remove the valve lifters/cam followers from the head.

Install a air pressure hose adapter into the spark plug hole, then apply compressed air pressure to the cylinder. Use a pressure regulator set to about 100 psig to maintain air pressure in the cylinder. The piston must be at the bottom dead center of the intake stroke, with all the valves closed.

Remove valve springs.

Remove old valve stem seals,

Install new valve stem seals on valve guides,

Replace valve springs.

Remove air pressure from cylinder move adapter to next cylinder in firing order.

Perform the above steps to the other cylinders after rotating the crankshaft to position each cylinder at BDC intake stroke, in firing order sequence, before applying compressed air pressure to the cylinder. After the seals on all the valve guides have been replaced, reinstall the cam shafts.

Reinstall valve covers and spark plugs/coil packs..

It would take me about 4 to 5 hours working steadily for me to do this on a six cylinder engine, care must be used to prevent errors with air pressure and removing the valve springs.

Once, I dropped a valve into the cylinder after removing the spring, due to lost air pressure in the cylinder. At first I was really angry because I thought the head would need to be removed to retrieve the dropped valve. Instead, after cooling down, I used a powerful little magnet placed in the end of a length of small tubing that would fit into the valve guide. With the tubing pushed down into the cylinder through the valve guide, I caught the end on the dropped valve stem and by slowly pulling the tubing back out of the valve guide, pulled the end of the dropped valve stem back up into the valve guide. Then with the valve back on the seat, reapplied air pressure and reinstalled the valve springs.

Parts needed for a 3.0l V6 are a set of 30 valve stem seals, and a new valve cover gasket set. If needed replace the timing belt and water pump at the same time to save labor costs.

[mcanedo92588]

Alright, I will get a quote for that but it will probably have to wait about a month or two. So from what I keep hearing, unless I get an OEM catalytic converter, the CEL won't go away? Why is this, and do I honestly have to do that spacer thing if I get the Magnaflow one?

[diagnosticator]

There are no facts that imply the Magnaflow cat won't operate without a CEL. Although it is more likely the cat will cause an occasional CEL/code, if that happens, a spacer for the post cat O2 sensor should fix that. The reason for this is because an inexpensive aftermarket catalytic converter uses a lot less precious metal catalyst coating on the core matrix compared to the very expensive OEM cat.

[mcanedo92588]

There are no facts that imply the Magnaflow cat won't operate without a CEL. Although it is more likely the cat will cause an occasional CEL/code, if that happens, a spacer for the post cat O2 sensor should fix that. The reason for this is because an inexpensive aftermarket catalytic converter uses a lot less precious metal catalyst coating on the core matrix compared to the very expensive OEM cat.

K, and I am assuming if I have this installed at a shop they wouldn't be feeling the "add this space for me so I don't throw a code" thing...?

[diagnosticator]

K, and I am assuming if I have this installed at a shop they wouldn't be feeling the "add this space for me so I don't throw a code" thing...?

I don't think so, but maybe it depends on how fussy the area emissions rules are. Maybe a bribe would work?

[SlickFix]

OP, as everyone else said, focus on the oil consumption and forget about the CAT for now. I've been riding around with P0421 and P0431 for over 3 years without any loss of performance in the engine. The only difference between my 3.0 and yours is that mine doesn't consume oil like yours does.

Good luck, let us know how things go.

[mcanedo92588]

OP, as everyone else said, focus on the oil consumption and forget about the CAT for now. I've been riding around with P0421 and P0431 for over 3 years without any loss of performance in the engine. The only difference between my 3.0 and yours is that mine doesn't consume oil like yours does.

Good luck, let us know how things go.

I will see what I can afford to do for now, but I have been trying to get this stupid oil thing taken care of for months but no one seems to know what they are doing around here and I am already several hundred in to just diagnostics. The next step for sure will be the valve stem seals, but I will have to see when I can get the work done and how much it will be. Thanks for all the help everyone, much appreciated!

[imnuts]

What was done with the PCV system when the shop looked at it? Was it replaced, cleaned, or just inspected? If it was replaced, what all was replaced. A clogged or improperly working PCV system can lead to oil consumption, though I wouldn't think it would cause as much as you're seeing, it certainly wouldn't help.

[mcanedo92588]

What was done with the PCV system when the shop looked at it? Was it replaced, cleaned, or just inspected? If it was replaced, what all was replaced. A clogged or improperly working PCV system can lead to oil consumption, though I wouldn't think it would cause as much as you're seeing, it certainly wouldn't help.

I think they just tested it, I think it was this and the crankcase they pressure tested if I am not mistaken?

[Chard_bb6]

I am thinking about just doing this for the cat for starters, any thoughts? Looking to just get it done fast and cheap but still decent.

http://www.ebay.com/itm/321350216074...84.m1423.l2649

How were you planning on getting these on? Cutting the old ones and welding these in place? On the same boat minus the oil consumption. P0421 and the occasional random misfire codes.

[mcanedo92588]

Yeah, I guess... but apparently I need to worry about just the oil consumption right now. The guy I usually have do this stuff for me doesn't want to touch the project because he doesn't want to owe me a new engine if something messes up. I am probably going to have to cross my fingers and hope for someone really skilled willing to help me from here that lives pretty close. diagnosticator, ever in the Portland area?! :)

[diagnosticator]

Yeah, I have some weird consumption problem Audi couldn't even diagnose. I go through about 1.5 quarts every 1000-1200 miles, pretty ridiculous but it doesn't seem to be causing any problems or whatever, no leaks that are noticeable so everyone I have had look at it is baffled. I am just wondering what my best options are for getting it replaced, should I just get the magnaflow 2.25 inch one and be done with it? Also what is the bank 1 mean, is that just 1 of them is going, I am assuming drivers side or left would be bank 1 correct? Anyone with some more knowledge than me, please let me know what I am looking at here. Thanks!

Audi has stated in other high lube oil consumption cases, that 1 liter of make up oil every 1000 miles is not excessive oil consumption. Audi would say this was the case if the engine burning that much oil, was still covered by the Factory warranty. Since the dealer could not make a diagnosis, did they charge you for the work?

[mcanedo92588]

Yeah, $125 for nothing. :/

[mcanedo92588]

Going to get the cat replaced tomorrow, just to confirm it is the passenger side one that is below the car right? When I called the exhaust shop he asked if I knew if it was that one or the one near the manifold and I told him I don't know. All I know is the code is p0421 and says bank #1. The difference is like 4 hours extra worth of labor and money so I am just hoping it is the cheaper easier one. If anyone can verify before tomorrow morning that would be great.

[Samsonite]

JHM's website says this: Bank 1 = passenger's side/right, and Bank 2 = driver's side/left...

http://jhmotorsports.com/shop/catalo...-v6-p-990.html

[mcanedo92588]

JHM's website says this: Bank 1 = passenger's side/right, and Bank 2 = driver's side/left...

http://jhmotorsports.com/shop/catalo...-v6-p-990.html

Sorry to sound ignorant, but there is only the 1 near the manifold correct? So there would be a different code and it wouldn't say left or right side if it was that one? Just want to make sure I get the correct one replaced, but the last time I ran the scan was like a month ago so maybe now they are both bad lol. I just happen to get this damn car right at the point where everything goes bad and needs replaced after I purchased it...

[imnuts]

There are 2 cats on the 3.0, both are near the exhaust manifold, and they are labeled based on which bank they are on, as per the info from JHM's website. Bank 1 (cyl 1, 2, 3) are on the passenger side and bank 2 (cyl 4, 5, 6) are on the driver's side. I'm not sure what you're seeing under the car, but there aren't any cats there.

[road_tripper]

depending on how persistent the code is... you could do what the rest of us do and clear the code when it shows up, and schedule the emissions test during a 'clear' time.

my passenger cat has been throwing the P0421 intermittently since at least 2010. I clear the code and drive on.

[SJorge3442]

I get the 421 code all the time. Depending on how long I stay in 4th gear around 40 mph. If I am in that combo for about 25 seconds, the code comes on immediatly. I just clear it. Takes me 20 seconds using Torque with my Appradio2. Plus it gives me a chance to check out other stats. I have been getting a code for a disconnected or non functional o2 sensor on the passenger side.....do I care? Not really. I stopped caring a long time ago.

[mcanedo92588]

I actually have a bit of an oil burn problem and get quoted ridiculous amounts to fix it. I think that is what lead to the cat going bad for now, so I honestly think I might just fix the cat to get rid of the code because I really don't want to have any engine problems if for some reason it gets clogged, and then look towards trading her in. :/