P0420 O2 Sensor Location
Thread Starter
Junior Member
Joined: Apr 2024
Posts: 21
Likes: 2
2010 Mercedes E550
P0420 O2 Sensor Location
Hello world,
I own a 2010 Mercedes e550 with 188k miles on the dash. The car is phenomenal except I have a small issue. The P0420 code keeps coming on. I know that it could be the cat but I wanted to try to throw on some new bosch o2 downstream sensors before shelling out the money for a new cat. Because of the mileage, I’m assuming the o2 sensors are going out anyways. The code comes on and off, usually around the time I fill it up with Shell premium gas? And then it goes out after driving it for a couple days. Or sometimes the light goes out when I fill it up with gas and then start it. It’s so weird. It doesn’t happen all the time, so I assume it’s probably a sensor issue. It’s just annoying and i don’t know why it keeps happening. I would like to attempt replacing the sensor by myself, however I can’t find any videos on YouTube or any instructions on here. I may just be missing it but if someone can guide me in the right direction that would be great. I know you probably need some special tool to remove the sensor so if you know what that is that would be great as well. But yes if anyone could direct me on how to get to them and remove them I would greatly appreciate it. Thank you
I own a 2010 Mercedes e550 with 188k miles on the dash. The car is phenomenal except I have a small issue. The P0420 code keeps coming on. I know that it could be the cat but I wanted to try to throw on some new bosch o2 downstream sensors before shelling out the money for a new cat. Because of the mileage, I’m assuming the o2 sensors are going out anyways. The code comes on and off, usually around the time I fill it up with Shell premium gas? And then it goes out after driving it for a couple days. Or sometimes the light goes out when I fill it up with gas and then start it. It’s so weird. It doesn’t happen all the time, so I assume it’s probably a sensor issue. It’s just annoying and i don’t know why it keeps happening. I would like to attempt replacing the sensor by myself, however I can’t find any videos on YouTube or any instructions on here. I may just be missing it but if someone can guide me in the right direction that would be great. I know you probably need some special tool to remove the sensor so if you know what that is that would be great as well. But yes if anyone could direct me on how to get to them and remove them I would greatly appreciate it. Thank you
Last edited by E550Rizzy; Jul 22, 2025 at 09:16 PM.
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,769
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Save your efforts rushing to your downstreams sensors.
Troubleshoot what your problem is first: cats on ZDDP oil ?
How much oil does your engine use ?
Troubleshoot what your problem is first: cats on ZDDP oil ?
How much oil does your engine use ?
Last edited by CaliBenzDriver; Jul 23, 2025 at 12:10 AM.
Thread Starter
Junior Member
Joined: Apr 2024
Posts: 21
Likes: 2
2010 Mercedes E550
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,769
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Thread Starter
Junior Member
Joined: Apr 2024
Posts: 21
Likes: 2
2010 Mercedes E550
Out Of Control!!
Joined: Apr 2019
Posts: 11,921
Likes: 6,769
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Last edited by CaliBenzDriver; Jul 23, 2025 at 02:24 AM.
MBWorld Fanatic!
Joined: May 2012
Posts: 2,359
Likes: 1,555
From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
Hello world,
I own a 2010 Mercedes e550 with 188k miles on the dash. The car is phenomenal except I have a small issue. The P0420 code keeps coming on. I know that it could be the cat but I wanted to try to throw on some new bosch o2 downstream sensors before shelling out the money for a new cat. Because of the mileage, I’m assuming the o2 sensors are going out anyways. The code comes on and off, usually around the time I fill it up with Shell premium gas? And then it goes out after driving it for a couple days. Or sometimes the light goes out when I fill it up with gas and then start it. It’s so weird. It doesn’t happen all the time, so I assume it’s probably a sensor issue. It’s just annoying and i don’t know why it keeps happening. I would like to attempt replacing the sensor by myself, however I can’t find any videos on YouTube or any instructions on here. I may just be missing it but if someone can guide me in the right direction that would be great. I know you probably need some special tool to remove the sensor so if you know what that is that would be great as well. But yes if anyone could direct me on how to get to them and remove them I would greatly appreciate it. Thank you
I own a 2010 Mercedes e550 with 188k miles on the dash. The car is phenomenal except I have a small issue. The P0420 code keeps coming on. I know that it could be the cat but I wanted to try to throw on some new bosch o2 downstream sensors before shelling out the money for a new cat. Because of the mileage, I’m assuming the o2 sensors are going out anyways. The code comes on and off, usually around the time I fill it up with Shell premium gas? And then it goes out after driving it for a couple days. Or sometimes the light goes out when I fill it up with gas and then start it. It’s so weird. It doesn’t happen all the time, so I assume it’s probably a sensor issue. It’s just annoying and i don’t know why it keeps happening. I would like to attempt replacing the sensor by myself, however I can’t find any videos on YouTube or any instructions on here. I may just be missing it but if someone can guide me in the right direction that would be great. I know you probably need some special tool to remove the sensor so if you know what that is that would be great as well. But yes if anyone could direct me on how to get to them and remove them I would greatly appreciate it. Thank you
