pardesi

I recently had quite a bit of codes pop up on my 2012 E550 (86K Miles) and was able to debug them. Figured I post it here incase others run into similar issues.

Few weeks ago while driving my check engine light started flashing and was not getting much power to the engine (knew it was a misfire). I was a block away from AutoZone so decided to have them pull the codes.

Following codes popped up: (all on one side of the engine)
P0300 - Multiple/Random Misfire Detected
P0305 - Cylinder 5 Misfire Detected
P0306 - Cylinder 6 Misfire Detected
P0307 - Cylinder 7 Misfire Detected
P2179 - System Too Lean Off Idle Bank 2
P0308 - Cylinder 8 Misfire Detected

Had the car towed home and order new spark plugs from Napa. After installing the plugs and resetting the check engine light the misfire codes went away and following new codes were detected. The car ran much better and drivable but the check engine light was on.

P0367 Camshaft Position Sensor "B" Circuit Range/Performance
P0366 Camshaft Position Sensor "B" Circuit Range/Performance
P036700 - The position sensor for the exhaust Camshaft (Cylinder Bank 1) has a short circuit to ground.

Ordered 2 new Camshaft sensors from Napa and replaced the ones on Bank 1 (side - Cylinder 1,2,3,4). After the reset, check engine light went away along with all the error codes. Knock on wood, been 4 days and 150 miles later no check engine light and car is running excellent.

Hope this info helps others in future and I don't run into any more issues. Thanks!

PS: my extended warranty had just expired three weeks ago ... my luck!

Arrie

Thank you for a very good post. Just one question- What is the bank one on the engine, driver side or passenger side?

pardesi

Bank 1 is the passenger side. Thanks

pardesi

Thought I had this figured out after driving 185 miles, back to square one with all the misfire codes noted above. I think I have to focus on this code:

P2179 - System Too Lean Off Idle Bank 2 (air/fuel ratio)

I could tell the car started running poor prior to check engine light coming on and flashing.

If anyone has any info they can share that will be great.

Thanks

Mud

I saw your first post and was wondering if/when codes may re-appear. I was hoping that maybe your parts did the trick but to be honest I was a bit doubtful due to the number of codes. In many cases the random misfire is not due to ignition - it can be from a number of sources, vacuum leak, injectors, fuel pressure, etc.
The first suggestion is to not buy more stuff until you figure out what's going on. It's likely that a single issue that is driving several sensors out of range and not several things that happened to go wrong at the same time.

Do you have a scan tool or are you relying on Autozone? If not, now is a great time to get one, preferably something better than the generic (modes 1-4) obd tool. And a wiring diagram.
I would start by looking at (1) real time run data that shows fuel trims, O2 voltages, MAF readings, etc. and (2) freeze frame data that captures sensor data at the time the code was thrown. This can help to start eliminating items that are ok, which is important as it can help focus on what may not be ok.

I agree with you to look at the P2179 code for now, don't worry about the misfiring for the time being.
I would suspect that the short term fuel trims will be high (over 3-5%) and that long term fuel trims will be over 20%. System too lean means that the pcm is putting more fuel into the mixture, causing long term fuel strategy to go rich out of range and thus the code. If the fuel trims are high at idle and return to normal range at 2500 rpm (approx.) then a vacuum leak may be an issue. Start simple and check vacuum lines, seal at throttle body inlet (where MAF sensor is), pcv system.

It's curious that the cam sensors showed as out of range - my suspect in this case is the circuit and not the actual sensors. By circuit, I mean the wiring and connectors to that bank. A corroded pin connector, bad wire, poor ground can cause the individual sensors to get confused even though they are actually ok. Also, if the cam sensor data is *****, this can also contribute to the misfiring, as the ignition firing/injector pulse is not correlated with proper cam (valve) positioning. Again, start simple and check the wiring and connectors and also check all cam sensor and phaser connections for oil (unplug them to look). If there is oil inside the connector, not good, it can wick into the harness.

After checking the basic stuff, if you aren't able to look further at run data, it may be prudent to get the car diagnosed at a good local indy mechanic if you have one around. Dealer is also an option but more expensive. However the cost of a good diagnosis may outweigh guessing at what may be wrong - I don't mean that badly or to offend - just focusing on looking at what the data is showing.

pardesi

Thanks for the info.. when this first happened I was thinking the same, how can all 4 spark plugs go bad. I have a ieGeek scan reader. Let me see if I can pull some of this data.

I did have oil in the camshaft sensors harness that I had replaced.

Will look at few things you noted and see what I can find. Thank you.

pardesi

I am not the best at reading this data but looks like the Long Term fuel % trim on Bank 2 is very high compared to Bank 1. Bank 2 is where all my issues are at.

Mud

Just to clarify about the cam harness - are you saying that you saw oil in the harness but left the harness in place? If so, that oil should be cleaned as much as possible, all other cam sensor/phaser harnesses should be checked as well. MB has sacrificial pigtail harnesses that can be installed, I've seen them on ebay as well, but the preferred fix is to replace the leaking sensor or phaser. Oil in the harness can cause circuit issues on a variety of components.

I assume that was freeze frame data that you posted? Shows vehicle speed as 76 km so I'm thinking that's what was going on at the time the ECU posted the misfire code. Offhand other than trying to figure out the fuel rail pressure conversion it generally looks ok except for LTFT B2. What's interesting is that the STFT's B1 and B2 are both good but the ECM was trying to overcome a lean condition on B2 by remaining very rich on the long term fuel strategy. It would be helpful to see run data at idle to see what the fuel trims are doing. Reason is that if there is a vacuum leak that's air not metered by the MAF and impacting STFT at idle (too much air, running lean), causing STFT to go high (rich). At higher speeds the engine is overcoming the extra air and the STFT therefore drops back to normal range, which will also allow LTFT to begin to drop back to normal range. But your LTFT B2 looks to be remaining very high, possibly from the misfire. There is also some data missing, such as MAF and O2 sensor readings but it is what it is.

To avoid running you ragged with internet diagnosis, I think it's going to need further hands-on look at additional sensor and module data and ignition/electrical. The cam trouble codes you saw before can be worrisome, as that circuit could be the base culprit of the misfiring and high LTFT B2. I could ask a dozen questions about sensors and components but most of this is going to need to be actually looking at the car and eliminating components as sources of trouble. Some of that may take tools that you may not have, so it may be cost effective to get an outside diagnosis.

But as mentioned, at least do the simple stuff, check for a vacuum leak, including the intake base gasket, hoses, pcv, etc. Check wiring integrity, etc. I've encountered a "duh" moment on more than one occasion where I have looked for the big problem when the little problem was right in front of me.

pardesi

Correct on the oil. Just pulled them from bank 2 and can see the oil. Will try to clean up as much as I can. I agree on debugging this over the net and most likely will take it to the dealership.

Appreciate the feedback and input.

Mud

Sorry to see that oil, but hopefully you've caught it in time. I don't have WIS up in front of me for a wiring diagram but I'm thinking that the 3-wire cam plug in the picture may have leads for power, ground, and reference signal. Wonder what the PCM is seeing to/from that connector and if it's a possible issue. I also see the secondary O2 sensors listed with no fault codes, but those are essentially narrow-band sensors checking catalyst efficiency. The more detailed data comes from the primary wideband O2 sensor voltages, especially on Bank 2 with the high LTFT.

I hope that as you go further you post up details and progress (success) so we can learn what happened here.

pardesi

Agree, I will keep everyone posted on the progress. So I decided to clear the codes and check engine light went away with no codes after cleaning the oil but thinking all that had had nothing to do with it. My cousin swung by and we used his reader and got some good data at idle.

The LTFT2 reading is still higher then 1
Also the O2 Bank 2 sensor 2 voltage is low

Both are on the bank2 so something is going on and just a matter of time before the misfires happen again. Something more for me to look into. For now the car seems to be running fine, but the data between bank 1 and bank 2 is not the same.

Mud

That's good info. I see the LTFT is starting to come down but STFT is a bit high. I suspect the higher STFT is due to the O2 sensor voltage and the declining LTFT may be helped by elimination of misfire (perhaps from the oil in that connector). However I would expect LTFT strategy to still run higher due to the increased STFT until core issue (possible O2 sensor) is resolved. See what you think....

The oil in the connector can absolutely interfere with any low voltage reference signal from the sensor or phaser. As mentioned, if the pcm can't understand where the particular cam is positioned in relation to ignition/injector, it can throw a misfire code.

Also, that low voltage from the primary O2 is telling the pcm the mix is running lean, causing the pcm to increase fuel, possibly source of the high STFT and high but declining LTFT. The pcm relies on the O2 sensors (when in closed loop) to tell it if there's too much oxygen (lean) or too little oxygen (rich) in the exhaust mix. The pcm constantly adjusts the mix (STFT). If voltage is low then STFT will increase to add fuel. If over about 5% (generally) then LTFT will start to increase. If LTFT goes over range (generally 25%) a code can be thrown.

To my thinking it would not be unreasonable to consider replacing that B2 primary O2 sensor as it appears to be having an impact on the fuel trims. It's not a costly item just a bit fiddly to get under there. Also suggest ensuring every one of the 8 cam connectors (4 per bank) be checked and cleaned if needed, with any leaking component replaced. Again, an internet diagnosis so use your judgement - my comments are based on what the data is showing and I've assumed you've checked for any possible vacuum leaks. Looking at what appears to be borderline vacuum reading and MAP sensor (pressure) reading at idle, I think that a vacuum leak factor should be further investigated.

pardesi

All great info. I need some sort of a diagram to trace the vacuum lines (visually what I could see looked fine) . But yes on the cam sensors check and will re look at them. I am driving the car now and keeping an eye on the gages. All current failure are pointing to the OS2 sensor fail.

For the fun of it, I ran the reader on my other Benz (GLS) and everything came back good as expected. I can post the results if one wants a comparison.

It will take me sometime to look into all of these but will keep you posted.

Thanks

pardesi

Quick update:

Only thing I have done is cleaned the oil from the cam wiring harness. After driving the car for a while, the misfire and O2 sensor issues I was seeing are gone. Thinking all the carbon that came on due to earlier misfire is cleared up.

Below is the latest data and past two days, car is running good. No oil on the connection but will check again on Sunday.

I am still concerned on the high numbers on the LTFT1 (even though my issues were on bank2 side) that is if I am reading it correctly. Will continue to monitor and do some research on the high ratios.

Thanks


Data snap shot not at idle speed:

Mud

Seems yes, there's an issue still in there. Not sure what speed/rpm these readings were taken.
For primary wideband sensor, perfect stoich ratio is 2.5 volt, equates to 14.7:1 air/fuel ratio. To be honest, I don't understand the AFR(c) ratio reading of 29.4, but I think it's running rich at that rpm. Your primary O2 sensor voltage is less than 2.5v and the secondary checking narrowband sensor also seems to bear that rich mix out, as perfect for that sensor would be hovering around .45v. However that snapshot may be within reason if the engine was under acceleration at the time.
STFT on both banks is running perfect but again that may be due to engine rpm overcoming any deficit. LTFT looks to be coming down but also perhaps due to rpms.

I understand that no further lean/misfire codes are being encountered since the engine data is currently within range of what the PCM can work with.
I think a path forward may be to simply monitor the readings to see which way they may trend, but I still suspect that primary O2 monitor.
Thanks for posting data.

EDIT - I was mulling over the impact of turbo application (I think your 550 is equipped) and other than perhaps more close monitoring of intet/outlet temps I believe that other parameters still apply. However, because of the increased air, the pcm may go rich to ensure against going too lean. Just a thought.

EDIT - maybe the data got stuck in my subconscious, but I got to thinking about the fuel rail pressure reading of 16840 plus the recorded 2 DTC's. I'm not sure what the units are for the 16840, plus I didn't see that rail fuel pressure vs what commanded pressure (what the ECM is looking for) was recorded. That can help determine if the fuel system is providing too little or too much volume or pressure. I would expect to see fuel pressure as psi or kPa, but if this is kPa, it doesn't make sense to me - doing the conversion yields equivalent of over 2400 psi so I must be doing something wrong. I would expect to see rail pressure of about 50-70 psi. I must be goofing up the conversion. However, there may be an issue with the fuel supply that may come up at a later time if indeed the readings were out of range.

pardesi

Quick update:

The car has been running fine and no check engine light thus far or any other error codes. Only thing I did was cleaned up the oil from the cam sensors plug and replaced a few that were leaking.

As for the fuel ratio that is still high and continuing to keep an eye on it.

Latest snapshot below: (at idle and 2500 rpm)

Mud

Thanks for posting. Those numbers look almost like classic vacuum leak or fuel supply issue. Fuel trims drop by around half at 2500 rpm.
But not out of ecu range so no CEL at this point.

pardesi

So my neighbor just picked up a 2014 E350 and I decided to pull the data from his car. I was surprised to see his numbers so high. My 2017 GLS is close to 0%, where it should be.

I may take it to a mechanic then, found out someone in town whom specializes in Mercedes.

I do want to Thank you for all of your help and assistance. Certainly appreciate it.

Prem Naidu

Hi
I have a mercedes benz w212 E250 cdi 4matic yr 2011
Can you help me locate knock sensor 2 (cylinder bank 1)
If you can share some photos will be great
Thanks

pardesi

I realized I never posted on what the actual resolution was.

In my case I caught it while driving and looking at the data I was reading. It was the oxygen sensor, amazing what that can do and how it was triggering all the codes and check engine.

Unfortunately it was in a tight position to reach and get to. I think I tried for good few days before giving up and taking it to the shop to replace it.

Once the oxygen sensor was replaced. Car ran great.

I still have the car with 108k miles and a tune. Runs awesome. All though I did break the driveshaft earlier this year and that was pricy . But the 500 plus hp makes up for it.

Ehtesam

Hey I recently got a check engine light and the code is p0366 and the reader says it is Bank 1 sensor 2. After taking a look at the sensors 2 of the magnets are leaking oil. so should I change the Magnets and the sensors or just the sensors.

pardesi

Sorry I would not know the answer to that one. Would have to do some more research to guide you.

CaliBenzDriver

Usually CPS start leaking before the solenoids do. Change all four pieces of a family each time at once then check every 10k for fresh leakers.