Corey Kearby

Hey guys,

I could really use some help here. I believe that my right side catalytic converter is clogged. I have come to this conclusion because the fault codes have read O2 sensor and multiple cylinder misfires. I replaced both downstream O2 sensors and the cleared the CEL light. Truck was running fine and after about 60 miles or so, the CEL light came back on and the truck began running really rough and lost power. Eventually, it stalled at a traffic light and I had to have it towed to my home.

The only codes that are showing are multiple cylinder misfires. The truck was due for a tuneup so I replaced all plugs, plug wires, and ignition coils. I started the truck and there was no change in performance. When I say it runs rough, it looks like it is going to shake itself off the motor mounts. After doing more research online and this forum, I have come to the conclusion that it is the right side catalytic converter that is clogged. The reason I think this is because all my cylinder misfires are cylinder 1, cylinder 2, cylinder 3, and cylinder 4. All of them on one bank of the engine.

I call my local shop and they give me a quote of $550 for labor and $2800 (list price at the dealership) for the catalytic converters from Mercedes. I am not considering using aftermarket converters because I have heard they are essentially useless and I will run into this problem in short order again.

Before I bite the bullet on this one, and because I have time on my hands right now, I did some more research on catalytic converters. The 5 liter engine in this vehicle was installed in other Mercedes vehicles during this time period so I begin looking for the same part number (minus the first 3 digits indicating the chassis) online to determine if I could find a cheaper version without the G-wagen "surcharge", if you will.

I did find is no other vehicle around the same age as my truck carries that part number: 463-490-52-19. What I did find is that 2015-17 E550's used this part number: 207-490-52-19. The list price on this part is $1100.

My question is: are these the same catalytic converters? Can I buy this part, have a muffler shop cut the new converters off of the existing pipe and install them in place of my catalytic converters (much like buying a universal converter and installation). I could not get an answer from the parts guy at my local dealership. Does anybody know the answer to this? Does anybody have a connection at Mercedes that might be able to answer this question definitively?

The last thing I want to do is waste money trying to save money. One last note, I have not replaced the CAM sensor which might be the only other part (that I know of) that could cause this type of engine misfire. The reason I have not is that I do not get a fault code indicating that is the issue.

Thanks for any all input! Stay safe and healthy through this pandemic...

~Corey

almostordinary

Hey Corey,

I'm just starting to get into the G-Wagon scene, getting up to speed w the trucks.

I have built quite a few of my own overlanding Land Rovers and now looking to complement my E63 with a G55.

Couple of things I would try, if you're handy w tools and trucks.

Get under the car and check out the O2 sensor... sometimes these go out, and will throw erroneous codes, especially with how the Banks read with O2 and fuel readings.

Not 100% sure how the CATs are on these trucks, but go down there as well with a bottle of thread buster and spray the bolts down 4-5hrs before you plan on taking things apart and remove the exhaust system, inspect the CATs with a hi Lumen flashlight.

Usually bad CATs will rattle as all the honeycomb material has disintegrated. I've been able to smack my CATs with a rubber mallet or even my fist to determine if there's loose material inside.

One thing that I will miss about the Land Rover community is that there are a ton of people that are hands on there, and while these trucks are becoming more attainable, the majority of the folks don't wrench on them.

Hope some of the above helps you out.

Looking forward to joining this group and shedding more insight on these trucks w the community that wrenches.

-Ian

Corey Kearby

Hi Ian,

Thanks so much for the response. I have replaced the two downstream O2 sensors. The one thing I have not done is bang on the CAT's to determine if they rattle. I'll let you know what I find.

~Corey

almostordinary

Solid.

Do these trucks have upstream and down stream 02 Sensors?

Corey Kearby

Yes, they do. Upstream and downstream on both sides. Four of them in all.

I did bang on the CAT's. They sounded solid...no rattling. I did notice that the right rear O2 sensor has not been replaced. A shop said they did that one and it's clearly not new. I did the left one myself without checking the right side. I'm guessing that may be my issue.

I'll get another O2 sensor tomorrow (hopefully they are in stock) and replace it myself.

almostordinary

Good call. O2 sensors are super finiky.

I've bought both Bosche and generic brands for my Land Rovers and each brand has always had a bad apple in the bunch. Usually an inexpensive place to start when dealing with these issues.

Floobydust

Before you go and replace the cat, the crank position sensor on the M113 G engine is a well known failure item (and when I say failure, I mean it can become flaky or fail completely after warming up). It's a cheap and easy R&R, so I would do that before I when down the road of replacing the cat.

Corey Kearby

I've considered doing that and the camshaft position sensor too. The only reason that I have not is that I have not thrown a code for that. But at the same time, I'm just using a Carista ODB port reader with the accompanying iPhone app. The cats are the last thing I want to have to replace especially considering the cost. Thanks so much for your input. If the O2 sensor doesn't work, then camshaft and crankshaft position sensors will be next.

Floobydust

When my CPS was failing it never threw a code, yet a new CPS resolved everything.

Corey Kearby

Just wanted to close out this discussion with the results of my findings. Based on the misfires from the entire right bank of the engine, the catalytic converters on the right side were tested and were completely clogged. New converter/pipes were ordered from Mercedes Benz and installed. Truck runs great now. Be aware of the cost of these converters though. List price is $2,800 for just the right side. I was able to get my mechanic to purchase online from a Mercedes dealership that offered it at $1,950. With shipping, labor, and a couple of gaskets the total was just under $3,300. How do you plan to spend your COVID-19 government check? lol

almostordinary

ha! Glad it all got situated!

paulunm

Did you determine your theory about the CAT part numbers wouldn't work? Interesting theory.