RichardS

Anyone know where to find the definition for this code? I cannot find it on my Star Service CD.

It might be "Ambient air temperature display temperature sensor " according to this post but I am skeptical as that exact same description is listed for 6 different codes. If it is this, any ideas how to do more problem determination? The temp display works fine.

Code seems valid as it reappears as soon as I start the engine after clearing it.

alx

Maf out of bounds

Ie maf going bad or unmetered air entering the engine.

Check all intake hoses and fittings. Did you replace air filters? If you did you need to reset engine adaptations via das.

RichardS

Thanks alx, where did you find that code? Wondering because the 2007 320 has 2 MAF sensors and hoping the code is specific to one or the other.

MAF reading on my OBDII device looks fine while running/driving, but is very high (well past a WOT reading) instead of zero when the engine is off. Perhaps the computer is ignoring the bad one while running, have noticed no difference in how it runs and fuel mileage has not changed. I'll experiment tomorrow unplugging one of them at a time to see if the readings change and prove one or the other faulty.

I'll also look for unmetered air but a bad MAF probably makes more sense since the code resets the second I start the engine. Would think anything but a huge air leak would take a while to make the MAF reading go out of range.

RichardS

I believe it is the right sensor, that one by itself gives very high readings. p1101 is set again immediately after clearing then starting engine. The left one by itself gives normal readings. Drove around a bit with just the left one connected and no codes were set. Cleaning the suspect MAF did not seem to make any difference so I'll get a new one soon.

Thanks again for your help. If you have a few moments I'd like to know where you found the code description, just for future reference.

alx

Glad you narrowed it down. It is a generic obd code for bad maf. The temp sensor code did not make sense. Also the engine mgmt module usually codes out with generic codes.

RichardS

I'm back again because the problem was not solved. Could not find a separate MAF anywhere so had to buy the whole intake pipe with two MAFs installed. MAF readings now look completely normal on my OBDII scanner and engine continues to run great.

Problem is the code is still being set. I have cleared it many times and it comes back as soon as the engine is started. So I really need to find a definition for that code, anyone know of a source for MB specific P1xxx code definitions?

RichardS

Have read codes with my two scanners and one at a shop, all show p1101. Subscribed to the online startek site, official MB documentation there does not list p1101 as a valid code for the 164 model with the 642 diesel. I'm still stumped, anyone have ideas?

alx

it is unmetered air.

did you reset engine adaptations via das?

RichardS

Thanks! I'm curious where you found the code definition?

I will do a careful check for any possible intake air leaks.

I do not have a das setup so have not reset adaptions. I'm guessing no, but is there a way to do that without das? The locay indy shops I've talked to will not work on the diesel so if das required I'm gonna have to take a day off work to get it done at the dealership.

alx

This is actually a common error and is always a Maf or a hose somewhere. Make sure your intake tract is mated properly to the intake manifold. The design is ****ty and you can misalign the pieces easily.

If you do your own repairs it will pay off to get your own das setup. It can be had cheaply ($350) and will pay off quickly.

And no, there is no way to reset engine adaptations without das.

RichardS

Sure enough, the inlet pipe from the airboxes to the turbo inlet was not seated all the way on the driver's side airbox. That airbox has a pressure sensor on it so could be the ECU wants to see a slight vacuum and did not due to the leak. That's what I'm hoping at least.

Code cleared, went for a quick test drive and no more codes. May not have been long enough of a test but I'm hopeful, we'll see what happens.

I agree on the poor design, when we bought the car (used) the inlet pipe was cracked where it mates to the turbo. So someone before me had apparently forced it on there and broke it. I _thought_ I was always careful replacing that but obviously last time I did not pay enough attention to the airbox connection, lesson learned.

Thanks again for your help.

alx

have a drink and be proud now

RichardS

Well no joy. Left on a trip after my last post and CEL came back on at first startup. Still P1101, no other codes. Any other ideas?

Runs great, gets same mileage as always, so no external indication of a problem.

alx

Get a harbor freight stethoscope ($5) and listen under the hood for false air. Also your engine adaptations need to be reset and all codes cleared.

RichardS

I finally solved this after buying a star multiplexer and installing xentry and DAS, a bit of a PITA but DAS gives much more detailed diagnostic data than you can glean from OBD codes. My guess is that p1101 is being set for multiple reasons related to MAF, DAS shows a whole bunch of detailed codes for various MAF errors. In my case it gave a specific code saying the left MAF value was out of range. After that MAF was replaced the DAS code went away and the p1101 OBD code was gone as well.