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Got a CEL on my 15 E63S with 57k miles on it which appears to be a bad O2 sensor 1 on bank 2.
These are the codes and what my iCarsoft scanner shows.
I ordered 2 new Bosch upstream O2 sensors and been searching the forums and YouTube to find a DIY write up on how to replace these but not found much.
Has anyone done this and have a write up or DIY you might share? I
From what I read the space behind the engine / firewall is super tight so you cannot easily unclip the connector from there and also need to go from the bottom to unbolt the sensor using a O2 sensor socket which I bought.
I am hoping to not have to drop the exhaust to do this which would clearly be the easiest way just more time consuming.
Thanks in advance. I may attempt this anyway and will share what I learn in a write up
You're right about accessing from under... it won't be easy - Clean Lambda will feel like a new engine...
I chime in to have you check oil in Lambda connector coming down from CPS harness.
You know it's really odd to get premature failure on emission parts.
Normally they are dirty/slow near 85kMi before the heater has a chance to quit near 150kMi...
The heater element in O2/Lambda is long lived with pulsed modulated current.
The other thing is the ECU MOSFET driver circuit maybe at fault...
You're right about accessing from under... it won't be easy - Clean Lambda will feel like a new engine...
I chime in to have you check oil in Lambda connector coming down from CPS harness.
You know it's really odd to get premature failure on emission parts.
Normally they are dirty/slow near 85kMi before the heater has a chance to quit near 150kMi...
The heater element in O2/Lambda is long lived with pulsed modulated current.
The other thing is the ECU MOSFET driver circuit maybe at fault...
I am assuming it’s a bad O2 sensor based on the codes I’m seeing??
I coincidentally also have both front inner CV boots leaking with a significant amount of boot grease under the car and am trying to assess when I get under the car if some of that grease got to the O2 sensor and is causing the code.
I’m in Illinois and I’m checking the warranty booklet I don’t see any extended emissions warranty coverage for that state unfortunately.
the fact emissions are scrutinized makes sensor not candidates to cut corner. Lambda sensor directs the engine control.
The injection logic relies on it to decide what to do.
I don't think the CV-boot grease has a chance to mess up unless it gets into connectir from the loose harness seals... possible but not likely. Worth checking visually.
If you've never delt with CPS or pigtails then that's prime candidates for quick check. You don't really want to compromise your new sensors with oil if that's the issue.
You're the inspector: keep an open eye to save your time. Don't rush passed clues...
🤞
the fact emissions are scrutinized makes sensor not candidates to cut corner. Lambda sensor directs the engine control.
The injection logic relies on it to decide what to do.
I don't think the CV-boot grease has a chance to mess up unless it gets into connectir from the loose harness seals... possible but not likely. Worth checking visually.
If you've never delt with CPS or pigtails then that's prime candidates for quick check. You don't really want to compromise your new sensors with oil if that's the issue.
You're the inspector: keep an open eye to save your time. Don't rush passed clues...
🤞
appreciate the advice @CaliBenzDriver as always ! i replaced all 4 of my CPS sensors a couple years ago as they did have oil and I checked 2 of them today and looked dry. I checked my cam magnets 2 of them and looking dry there too.
i'm going to research the codes a bit more because as you said these are not common to fail especially at 57k miles where I'm at so maybe its something else, but the codes are saying its that bank 2 upstream 02 sensor 1...
yes, heater circuit of passenger **DRIVER** side (B2) upstream lambda...
it can be a bad fuse... these don't blow without reason. unprotected wiring melt to exhaust ??
Do a little an overall visual to catch obvious clues to save time.
At least this is very well pin-pointed hard code. You're the surgeon ✌️
Last edited by CaliBenzDriver; Today at 04:50 PM.
Reason: B2: driver!!
I dont have that engine so i really have no idea how to replace those O2 sensors. I will say I recently had to remove my M272 passenger O2 sensors and I bought an ABN tool that helped me. I have the basic O2 sensor sockets and while i could get the upstream socket on I could not seem to get the ratchet on the socket. For the downstream bottom sensor I couldnt fit the socket on because the drive shaft was right up against it but I was able to just use a regular adjustable wrench oddly enough.
I had just taken it to a shop who managed to screw everything up. They actually broke the upstream sensor and they installed them back in the wrong holes. Guess i was lucky in that the sensors were removed recently so not that tight to remove again. Spraying with some liquid Wrench seemed to help, the sensor seemed tight at first so i sprayed Liquid Wrench, awhile after it came off easily.
Even with both sensors installed in the wrong holes I was only getting one code for the check engine light. 0443 "output for the heater of O2 sensor 1 (bank 1) has a malfunction.". After looking at sensor 1 its clear it was broken/bent.
yes, heater circuit of passenger side upstream lambda...
it can be a bad fuse... these don't blow without reason. unprotected wiring melt to exhaust ??
Do a little an overall visual to catch obvious clues to save time.
At least this is very well pin-pointed hard code. You're the surgeon ✌️
I dont have that engine so i really have no idea how to replace those O2 sensors. I will say I recently had to remove my M272 passenger O2 sensors and I bought an ABN tool that helped me. I have the basic O2 sensor sockets and while i could get the upstream socket on I could not seem to get the ratchet on the socket. For the downstream bottom sensor I couldnt fit the socket on because the drive shaft was right up against it but I was able to just use a regular adjustable wrench oddly enough.
I had just taken it to a shop who managed to screw everything up. They actually broke the upstream sensor and they installed them back in the wrong holes. Guess i was lucky in that the sensors were removed recently so not that tight to remove again. Spraying with some liquid Wrench seemed to help, the sensor seemed tight at first so i sprayed Liquid Wrench, awhile after it came off easily.
Even with both sensors installed in the wrong holes I was only getting one code for the check engine light. 0443 "output for the heater of O2 sensor 1 (bank 1) has a malfunction.". After looking at sensor 1 its clear it was broken/bent.
@TimC300 thanks for sharing this very helpful... assume you did all of your work from under the car correct? I think about all you can do from the top is attemp to unplug the connector but even that is difficult
@CaliBenzDriver when unplugged my oil solenoid I found that plug was leaking oil - glad I unplugged if nothing else but to find this oil creep
could that oil creep into the engine harness as well?
Peter, you did the right thing
I would not loose sleep over that because you got to it before it got to you.
You have plenty of good karma credits and a few spare ECU's on your shelves.
That connector is low down the engine belly, capilarity uphill not as fast as flat from CPS to ECU.
The interesting part is that everything connected to engine oil crankcase is now proven qualified to feed oil into the harness.... not just the specially sloted CPS made by Continental.
The question then becomes: "what other LEAK CANDIDATES are there?"
-- Cam CPS 4x + Pump solenoid: YES!
-- crank CKP: it's dry in the bell: No
-- coolant sensor is sealed by metal: No
-- oil level sensor: YES /TBD??
-- oil pressure sensor: YES /TBD??
-- VVT Solenoids 4x: Yes!!
-- ???
In the "leaky sensor chapter" we have a lot of room for improvement - RTV seal connectors from water intrusion :
-- Front/Rear bumper radars
-- Condenser pressure sensor
-- A/C compressor Clutch + PWM Valve
-- Ambient temp at bumper
-- front bumper pass. side harness connector
-- Both HL all connectors
-- Washer tank wirings pump + sensor
-- (Wheel ABS sensor are molded properly!!)
-- Front long range Distro. Radar connector
-- Misc. engine connectors
-- (ECU + ESP appear well protected)
-- Lambda + O2 sensors connectors
-- ISM all the way down under
-- "Main GND Strap" badly salted nut
Different engine, but I got the passenger side upstream sensor out from the top. Downstream sensor I got from the bottom.
On my M272 the passenger side O2 sensor connectors are connected up top near the throttle body. I took plenty of photos so i can look back and make sure i put things where they belong.
Heres the ABN tool on the upstream/top sensor: The hendle is only 10" long, if the sensor was on tighter I would probably benefited from using a length of pipe over the handle for leverage.
The wires were clipped at two locations, im guessing to keep them from hitting the drive shaft and exhaust.
The connectors were easy to unclip, once i figured out how the go on. Downstream connector pushed out forward, upstream push the tabs out on the sides and pull it up.
Adjustable wrench for the bottom sensor worked great.
After installing the bottom sensor I tied some string to connector and the old sensor and pulled it up from the top, bagged the connector so nothing falls in it while pulling it up.
Different engine, but I got the passenger side upstream sensor out from the top. Downstream sensor I got from the bottom.
On my M272 the passenger side O2 sensor connectors are connected up top near the throttle body. I took plenty of photos so i can look back and make sure i put things where they belong.
Heres the ABN tool on the upstream/top sensor: The hendle is only 10" long, if the sensor was on tighter I would probably benefited from using a length of pipe over the handle for leverage.
The wires were clipped at two locations, im guessing to keep them from hitting the drive shaft and exhaust.
The connectors were easy to unclip, once i figured out how the go on. Downstream connector pushed out forward, upstream push the tabs out on the sides and pull it up.
Adjustable wrench for the bottom sensor worked great.
After installing the bottom sensor I tied some string to connector and the old sensor and pulled it up from the top, bagged the connector so nothing falls in it while pulling it up.
@TimC300 these photos are super helpful thank you. I’ll try to add once I get into this job.
Quick q - did you (I assume) remove the airboxes on top and the insulation/soft cover on the plugs/wire area to get more space?
Today, 12:34 PM
