BUMP!, no help? The code is P0420 not P0423, has anyone removed the exhaust manifold on these engine, help would be great. Thanks.
Hello, I have code p0423 cat bank 1. I did a search on and found 4 possible fixes. I do now have a exhaust leak, I think its the manafold gasket, muffler shop looked at it. The coolant temp sender can cause the code also. The car did have misfires at some times, 3-6 months apart. New wires and plugs, no coil pack, strayed coil with water and no arcing or problems idling. The one item I would like to fix is the manifold gasket. I need some advice on removing the manifold, what to look for or any help to make the job go OK. I will replace the coolant sensor. The Jetta is a 02, 2.0 AZG. I really dont want replace the cat yet, big $$$. Thanks.
Fix the exhaust leak. That alone can cause a P0420, even if the cat is good.
Verify Lambda control and mixture (fuel trims). Check MAF and O2 sensor operation after the exhaust leak is repaired. Fix any vacuum leaks.
The exhaust manifold R&R is fairly straightforward: Remove the downpipe, disconnect O2 sensor, remove the nuts securing manifold to head, remove manifold. Fix any broken manifold studs, make sure the manifold isn't cracked. Then reverse the procedure to re-install. Service manual FTFW.
Thanks for the reply AnonyOOGt, I did start taking apart some items until I reached what I think is the EGR valve. The shield that is over the exhaust manifold has this valve bolted to it. There is a shinny silver pipe connected to it and runs under to the exhaust manifold pipe. I can not remove this connection, If I try to hard I'm afraid to break the pipe. I can not check the Lambda control, and what is that? Yeah it seems straight foward to remove, but getting there is the problem. Any more help would be great, and thanks AnonyOOGT.
That's the secondary air tube. Yes, exhaust-related fasteners have a tendency to seize due to their high operating temps.
Unfortunately there's not much I can do to help you with physically disassembling and re-assembling the car, as I'm stuck here on the internets. You're the guy actually working on it
Lambda control is VAG-speak for fuel trims/O2 sensor control. You'll need a scan tool (preferably VCDS) that can show data, not just codes, to check this.
Yeah I know that it's me doing the work on the car, but I just hate the fact that trying to take off something and you can't with out breaking it. I did find a 2 year old thread about someone trying to take off the same pipe and could not, he even took pictures. Never posted back if he took it off and how. So right now im stuck, I put back all I took off and figure out the next step. I really don't want to bring it to the dealer. Once again thats for the help.
Some heat on a pipe and valve that gets really hot, will that work, maybe. I thought about that adding heat, but wasn't sure do to the haet it is already exposed to. A muffler shop wanted $100 to replace the manifold gasket, i dont think they know what there in for. Maybe I will go that route.
Well I took the car back to Merlin muffler and they yold me it is the flex pipe leaking, They shown me the leak. I put my hand over the leak and felt exhaust coming out. Sooo its not the manifold gasket, good. But now it is the flex and cat unit all together. They quoted me $1300 for the job, ouch.
That's a much more common scenario. For a good OE cat, that price is about right. Yes, I've definitely seen leaky flex sections cause converter codes and O2 sensor/mixture codes.
What I do a lot of times, is get an aftermarket flex section, cut out the broken one, and weld in a new flex section, leaving the converter alone. I get about $200 for that.
Auto parts wholesalers. You probably won't be able to get one at Autozone. Measure your old flex, they're sold by size.
Mock it up in the car, tack it. You're probably going to have to remove The pipe to run a good bead.
OK, AnonyOOGT, this is the up date for what i have done so far. I went to Midus muffler and they looked at the leak at the flex pipe. Midus said they can cut in to the system and weld in a flex pipe. For $150 I went for it, no more leak. I will keep you up dated if anything else happens. Midus ended up removing the entire CAT. pipe, flex pipe in order to cut in to it. Big job I though for $150. Thanks for the help.
Midus? Midas? Haha.
Yep you've got to remove the whole pipe from the car to get a good weld on it. That's a good price, depending on where you are labor rates can vary. Here in NJ labor rates are definitely higher than the national average.