If I am looking at a used 1998 or 1999 BMW 540i , is there any way to tell if the catalytic converts have been changed? I found some for sale by owners or dealers and they don’t have a record from previous owners that they changed them. Can you look at them visually and maybe see a different stamp/logo/color/chape/welding...........that can tell you , maybe tap into the ECU of the car and know? I know that they go out between 50000 – 100000 miles but I want to be sure. Also once you change them with OEM do they again last 50000-100000 or they are better?
Catalytic Converters on 540i changed or NOT?
- Thread starter johny1
- Start date
One of mine was changed under warranty by the prior owner. I changed my other one at 93k miles because you could hear it srating to rattle as the insides disintegrated. They look identical to the old OEM assuming you use the OEM part. I don't know if you can tell a difference other than records from the owner or noticeably sloppy installation. They are bolt-on rather than weld-on for this model.
Any BMW dealer might have records on your car if warranty work was done but otherwise I think you'd have to find the exact dealership where it might have been done to inquire about out-of-warranty work. The original CATs are warrantied for 80k miles. The BMW warranty is not as good on the replacement OEM (2 yr?) although there is no reason to believe that they are any worse. I've only driven about 25k on one of the replacements and it's fine, but that's not long enough to notice a difference.
For what that's worth....
Also in researching replacements by aftermarket CATs, I was told from many sources that the aftermarket ones can be very crappy and the geometry of them can negatively affect performance (interior diameter at bend points as well as increased backpressure). I love to save money but I coughed up the $ for the OEM replacement. I didn't want to F-up my engine. Maybe if I do more research I can save money next time around. I'm in Florida so I can just take them off actually. We have no emmissions testing anymore.
Any BMW dealer might have records on your car if warranty work was done but otherwise I think you'd have to find the exact dealership where it might have been done to inquire about out-of-warranty work. The original CATs are warrantied for 80k miles. The BMW warranty is not as good on the replacement OEM (2 yr?) although there is no reason to believe that they are any worse. I've only driven about 25k on one of the replacements and it's fine, but that's not long enough to notice a difference.
For what that's worth....
Also in researching replacements by aftermarket CATs, I was told from many sources that the aftermarket ones can be very crappy and the geometry of them can negatively affect performance (interior diameter at bend points as well as increased backpressure). I love to save money but I coughed up the $ for the OEM replacement. I didn't want to F-up my engine. Maybe if I do more research I can save money next time around. I'm in Florida so I can just take them off actually. We have no emmissions testing anymore.
Can I just call the BMW dealer and give them the VIN to check for me? I did not know they are willing to do so. The problem is that sometimes the car came from a different state maybe and it will be hard to track the BMW dealer. Also I did not know the Cats are bolt on I thought they are welded to the pipe. Can you for example tap into the ECU and see if old Catalytic codes are stored there. Does the computer keep them or it deletes them as soon as they are fixed.
The guy above also said that one of his Cats went bad, I wonder If you simply failed emissioins or the ECU indicated that for you and displayed it on the dash? Thanks
The guy above also said that one of his Cats went bad, I wonder If you simply failed emissioins or the ECU indicated that for you and displayed it on the dash? Thanks
I couldn't tell you about the computer codes issue.
My first CAT was replaced by the previous owner under warranty and I don't know the situation causing it. The second one I did on my own just by noticing the rattling and break up inside. If you wait too long the insides will begin to possibly block flow and create backpressure to the engine. I figured sooner than later before a bigger problem resulted.
You should be able to call any dealer and give them your VIN. This will cover any WARRANTY tiems done at ANY dealer. If they give you a hassle then they have a serivice problem. Otherwise, you will have to figure which dealer the out-of-warranty-work was done and call them.
The CATS are welded to the pipe BUT the OEM replacement part consists of a 5 foot long piece of pipe starting from the exhaust manifold, with the CAT and extending past the CAT. That piece bolts on to the exhaust manifold and then to the remaining exhaust pipes downstream just past the CAT. I suppose it might be possible to find JUST the CAT piece and replace it by cutting and welding but I'm not aware if that is available (for that model).
My first CAT was replaced by the previous owner under warranty and I don't know the situation causing it. The second one I did on my own just by noticing the rattling and break up inside. If you wait too long the insides will begin to possibly block flow and create backpressure to the engine. I figured sooner than later before a bigger problem resulted.
You should be able to call any dealer and give them your VIN. This will cover any WARRANTY tiems done at ANY dealer. If they give you a hassle then they have a serivice problem. Otherwise, you will have to figure which dealer the out-of-warranty-work was done and call them.
The CATS are welded to the pipe BUT the OEM replacement part consists of a 5 foot long piece of pipe starting from the exhaust manifold, with the CAT and extending past the CAT. That piece bolts on to the exhaust manifold and then to the remaining exhaust pipes downstream just past the CAT. I suppose it might be possible to find JUST the CAT piece and replace it by cutting and welding but I'm not aware if that is available (for that model).
Not mentioned here, but the cats for the 98 and 99 540 I believe are covered under an 8 year/80,000 mile warranty. They are a known issue and most owners have gone down this road for replacement.
If it is time for replacement and you are out of warranty range, many people swear by the Magnaflow converters - you'd have to research the model number. The key is to get them TIG welded, and many auto shops have this ability. Rather than $900 each as the OEM are, they are like a couple hundred total and install is 30 mins. I would research this option further.
If it is time for replacement and you are out of warranty range, many people swear by the Magnaflow converters - you'd have to research the model number. The key is to get them TIG welded, and many auto shops have this ability. Rather than $900 each as the OEM are, they are like a couple hundred total and install is 30 mins. I would research this option further.
Well, amazingly, just had mine replaced! I went to the dealer yesterday with a rattling sound under my car. I knew it was the cats, not sure if it was one or two. I have a 1998 with 73K on it. Without any back and forth, and much to my surprise, the dealer replaced the cats with OEM parts - approximately $2K total, and I walked out the door paying nothing.
I definitely noticed a power increase again, but there were no codes or anything - just a rattling noice intermittently.
My first great experience at a dealership with my car!!!
I definitely noticed a power increase again, but there were no codes or anything - just a rattling noice intermittently.
My first great experience at a dealership with my car!!!