150200 Code Hanging Around
I've had this 2009 ML320 Bluetec since fall 2018 and have loved it. Gets 20-22mpg in the city!
About 6 weeks ago a CEL showed up so I put my BlueDriver OBD on it and it yielded a broad and vague code that pushed me to buy an iCarsoft. It shows 150200.
Long story short, in this order, I've done the following:
Replaced the y pipe, with new MAFs included. There was a crack in the coupler where it joins to the turbo housing.
Replaced the bleeder valve as there was oil inside the y pipe where the rubber gasket from the bleeder valve joins.
Replaced the air filters with Mann brand units.
Tested the MAF voltage before and after replacement. Both are 14.18V.
Checked battery and alternator performance. Battery is low, 12.17V at cold, alternator is pushing 14V.
At each turn, the CEL will clear with the icarsoft the first time I restart and then returns immediately on the next startup. I'm about to change the oil and replace the battery as part of scheduled/preventative maintenance and would like to know where to go next. I see that other posts around here go so far as to explore the possibility that the code is a "hard code" and will require xentry to clear. Others have said that you need to ensure that new oil levels never exceed 2/3 of the fill level on the dipstick.
Where should I go next??? Thanks for your eyes and your time!




I've had this 2009 ML320 Bluetec since fall 2018 and have loved it. Gets 20-22mpg in the city!
About 6 weeks ago a CEL showed up so I put my BlueDriver OBD on it and it yielded a broad and vague code that pushed me to buy an iCarsoft. It shows 150200.
Long story short, in this order, I've done the following:
Replaced the y pipe, with new MAFs included. There was a crack in the coupler where it joins to the turbo housing.
Replaced the bleeder valve as there was oil inside the y pipe where the rubber gasket from the bleeder valve joins.
Replaced the air filters with Mann brand units.
Tested the MAF voltage before and after replacement. Both are 14.18V.
Checked battery and alternator performance. Battery is low, 12.17V at cold, alternator is pushing 14V.
At each turn, the CEL will clear with the icarsoft the first time I restart and then returns immediately on the next startup. I'm about to change the oil and replace the battery as part of scheduled/preventative maintenance and would like to know where to go next. I see that other posts around here go so far as to explore the possibility that the code is a "hard code" and will require xentry to clear. Others have said that you need to ensure that new oil levels never exceed 2/3 of the fill level on the dipstick.
Where should I go next??? Thanks for your eyes and your time!
You can check here:
https://mbworld.org/forums/m-class-w...f-sensors.html
Or maybe you can take the advice about not using generic diag system on Mercedes. At your model, a reset of adaptation values for HFM is mandatory, after a repair. Not to mention about resetting the adaption values after Air Filters exchange.
My professional advice, use a specialized workshop for a correct maintenance, including parameters reset.
https://mbworld.org/forums/m-class-w...f-sensors.html
Or maybe you can take the advice about not using generic diag system on Mercedes. At your model, a reset of adaptation values for HFM is mandatory, after a repair. Not to mention about resetting the adaption values after Air Filters exchange.
My professional advice, use a specialized workshop for a correct maintenance, including parameters reset.
Thanks a lot for the response! I had seen that one and it motivated me to swap filters and make sure the bleeder valve was doing it's job. However, that post didn't mention any resetting of the adaptations. Is an air filter job really the delineator for a thorough diagnostics adjustment?




Also, any trained technicians knows that after any repairs at air intake, the HFM need to be reseted.
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Last edited by E55Greasemonkey; May 30, 2022 at 12:21 PM.






