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View Full Version : Troubleshooting Code P0101


Expert Marine
01-16-2014, 07:16 AM
I replaced the MAF and the problem is still there... I started looking for intake air leaks, and found this valve. It pulls oil fumes from the engine and sends them into the intake. This looks to be where most of the oily residue in my charge pipes is coming from... Whats it's purpose? What does that sensor do?

Any pointers?

lindenengineering
01-16-2014, 11:42 AM
That is the engine breather vent valve.
It is there for controlled venting of crankcase gases into the induction system.
The diaphragm often ruptures or deteriorates allowing oil & residues to flow into the induction system and cause excess carboning.

It is a servce item and should be replaced when showing signs of high oil passover if no other symptoms exist.

Your code reader doesn't explain the whole story, the tool isn't showing you the sub code which is actually triggering the fault. You will have to do an ohm out & volt check to check for such things as implausibilty, voltage feeds and outputs etc. The MAF sensor is particularly prone to showing faults when flow is affected or even the socket unplugged with the IGN on.
So beware.
Dennis

Expert Marine
01-16-2014, 05:52 PM
by it's design it looks like the spring allows it to stay open while there's low vacuum in the intake, and when there's higher vacuum it would close the diaphragm.

I'm just brain storming here, but why have the spring in it at all?



RE: Code. What's interesting is it that it shows pending right after clearing it. Like it can tell something is bad before the engine is running. Is there a test I can do with a multi meter to see if the sensor is within spec?

It sounds like I need to find someone that has a Star reader...

showkey
01-16-2014, 10:18 PM
It sounds like I need to find someone that has a Star reader...

YUP. Or some other scan tool with a sensor data stream. But even with a data stream you still need to know what a known good sensor value is to determine if yours is good or bad. There are learned skills needed to interpret the scan tool data. Shop manual data is great in this area either:idunno:

The real full code would also help..........example high voltage = possible loose connection, low sensor voltage possible short etc etc

vertigo
03-21-2014, 08:46 PM
RE: Code [P0101]. What's interesting is it that it shows pending right after clearing it. Like it can tell something is bad before the engine is running. Is there a test I can do with a multi meter to see if the sensor is within spec?

It sounds like I need to find someone that has a Star reader...

I've been seeing the same DTC code on my 2007 Sprinter which ahs been suffering with the turbo boost locked out 100% of the time. My local Sprinter tech's factory-level scanner identified the real DTC as 2623-001: Charge Air Offset Drift at Idle. The really odd thing is that he could not clear the code despite multpile attempts.

I looked up this DTC and its proposed remedial actions on the Sprintertek infobase website. Of special interest was the instruction to reset the adaptation data for the Hot Film Mass Airflow Sensor.

And so on my request my tech initiated his scantool's routine to do the adaptation reset, which completed with a confirmation of the reset. However, upon immediate rescan, the 2623 code was still there, even without any engine restart! We were left scratching our heads and contemplating what to try next.

I decided in the meantime to drive the van back to my shop (still sans boost) until we formulate our next course of action. But, on the third engine restart since the MAF sensor adaptation reset, the turbo boost was back on - noticeable and audible, at least for about 30 seconds, then locket out again until the next key restart of the engine, at which time boost is back on again for awhile.

This, at least is progress! More to follow.

flman
07-12-2015, 10:52 PM
I've been seeing the same DTC code on my 2007 Sprinter which ahs been suffering with the turbo boost locked out 100% of the time. My local Sprinter tech's factory-level scanner identified the real DTC as 2623-001: Charge Air Offset Drift at Idle. The really odd thing is that he could not clear the code despite multpile attempts.

I looked up this DTC and its proposed remedial actions on the Sprintertek infobase website. Of special interest was the instruction to reset the adaptation data for the Hot Film Mass Airflow Sensor.

And so on my request my tech initiated his scantool's routine to do the adaptation reset, which completed with a confirmation of the reset. However, upon immediate rescan, the 2623 code was still there, even without any engine restart! We were left scratching our heads and contemplating what to try next.

I decided in the meantime to drive the van back to my shop (still sans boost) until we formulate our next course of action. But, on the third engine restart since the MAF sensor adaptation reset, the turbo boost was back on - noticeable and audible, at least for about 30 seconds, then locket out again until the next key restart of the engine, at which time boost is back on again for awhile.

This, at least is progress! More to follow.

So did any thing ever become of this? Happy ending? :popcorn:

flman
07-19-2015, 03:43 PM
Mine turned out to be a dirty air filter, and I picked up and STP one on a Sunday, and the problem remained. So it went to the dealer, they re-adapted the offset drift on the MAF, and it still was in limp until they put in a OEM Filter. So if you have this code try a Mercedes Benz air filter first.