I have a 2009 ML 320 Bluetec 3.0 L turbocharged V6 with a persistent fault code P0101. Replaced MAF sensor, air filters and calibrated the ECU to adaft to the new sensor & air filter at the Mercedes dealership, fault code disappeared for a while but after 2 months at the middle of traffic jam in a hot summer day the same code appeared again. Erased the fault code but keep coming back. I do not want to come back again to Mercedes dealership and spend another $1000. I would appreciate any advise or comments as I will just try to trouble shoot it myself this time. Did not find any leak on air intake and turbo discharge pipe joints as well as the inter-cooler inlet and outlet connections, No hesitation, idle is excellent, did not noticed any power reduction or increased fuel consumption.

 

Your Mercedes dealer should warranty the part and/or their work.

 

Renato, CDI vehicles do not have "P" codes, they have six digit codes as seen in the PDF.

Secondly, your code reader is just that, a simple code reader and it is storing old W163 MAF codes. CDI vehicles have two MAFs so how does this P0101 code tell you which MAF is the problem? It doesn't.

Conduct the test for each MAF, one at a time, and compare the voltage readings. Understand that MAF Sensors are individually available.

Also note that right side and left side for any component is viewed by sitting in the vehicle and not facing the engine.

 

Thank you for your comment, unfortunately, MB dealership did not warranty the work because they only perform calibration of the ECU to adaft to the newly installed sensor and air filters, I myself bought and installed the brand new MAF sensor and air filters from MB dealer after confirmation from a reliable EuroCar technician with MB scan tool confirming fault code P0101 and diagnosed that MAF sensor need replacement.. But prior to see this independent Eurocar technician I was able to check the 11-12V power supply and ground continuity to and from the sensors OK and also the reference 5V signal voltage (it was actually 3.0 - 4.0 V) seams to be OK. But measuring the voltage across the Green/Yellow 5V reference signal wire back to ECU and the Blue signal ground I only got between 0.5 - 0.6 V @ 700 rpm and 0.7 - 0.8 V @ 3000 rpm. Reading was low I should get at least 2 V for a good MAF sensor.

 

Thank you very much for your response.You are probably correct because at the beginning I was using an Autel 419 OBD scanner revealing P0101 that is why I seek 2nd opinion from MB technician with MB scan tool to confirm the P0101 fault code. I am ordering from Amazon the correct scan tool for MB, I think it is Carsoft 980i MB scanner. As explained from my recent thread, I already checked that 12V power supply and 5V reference voltage from the MAF sensors OK but not satisfied with voltage readings while engine is running at 700 rpm and or 3000 rpm.

 

don’t be too quick to replace the MAF $500 sensors. Any issue along the air path can produce the code. I got one with the left MAF sensor. I cleaned the sensors and swapped positions. Same left sensor code. Cleaned the MAP on the manifold and was good for a year. This year the MAP sensor replaced but code remains. Map sensor on air box?

save the plastic antlers for the break and only the whole antler with MAF sensors are sold as a unit.

 

Yes it was the map sensor in the air box on my bluetec. Replaced it today. Green lettering and not interchangeable with the MAP sensor on the manifold. About $30 for each Bosch map sensor.
Anything that changes the air flow characteristics will trigger a P0101 on Mercedes turbo.

 

What were the voltages? Are you measure from the outer pins or the center pin? Your scanner live data should show if your maf sensors are responding.

 

I was able to fix the problem of persistent fault code P0101 on my 09 ML 320 bluetec. Is was only to reset the adaptation values each time you replaced the MAP sensor and/or the engine air filters with a brand new one. You will need to communicate with the ECU by using Foxwell NT 530 scanner with the Mercedes Benz, Sprinters and Maybach software loaded on it already plus other vehicle software of your choice. Without doing this reset of adaptation values, this fault code will keep coming back and without this scanner you will have to go to the dealership using the MB star scanner and be charged $ 250 -$350 for that plus the cost of air filters. Or buy the expensive Xentry DAS software plus accessories which may cost over $ 2000. I bought this scanner online from Ali Express.ca for C$ 285.51 include shipment and with Toyota software too for my other vehicle. I can use this scanner not only for adaptation of sensors but also for reset of transmission, service & maintenance reset, steering angle reset, brake bleeding, Knox /lambda sensor adaptations, DPF regeneration etc... . Other MB professional scanners like the Icarsoft Mb V2.0 is unable to do those adaptation.

 

Thanks for the tip. rrvtechcon

I found a crack on the right intercooler hose.
Do the right and left intercooler hose have about the same life span. In other words, is it time to replace the left intercooler hose at the same time?
I found aftermarket hoses for the right hose but not for the left hose intercooler.

Did you replace the whole anthers? What are you going to do with the old plastic part of the MAF holders, 6420908237 ?
My anther is cracked.
David

 

If your MAP sensor housing or y pipe is cracked then air will leak, this air may not be able to measure by your MAP sensor. You should replaced it to avoid fault code and eventually affect idling, power and acceleration later.
If you will ask me, I will replace both intercooler hoses but you may also replace one hose first then replace the other one when it becomes defective, however if are planning for a long trip, for your peace of mind I would replace it. Leakage from intercooler hose can caused fault codeand eventually affect idling, power and fuel consumption.

 

For those of you experiencing the p0101 code, check the map sensor on the back side of the throttle body. I found mine blown out and air leaking. I reinserted the sensor and connected wires that fixed my issue.