ml320 code p0105
 

started coming on a week ago it came in with a egr code don't remember code, looked over engine saw nothing and remembered wife got gas so checked cap and it was loose, so cleared codes and 105 keeps coming back, no vacuum leaks(used wd40) runs just the same, did a search not a lot of info as know one finished thread saying they fixed problem, so do I replace sensor and which one, thanks

no answers

P0105 correlates to the MAP Sensor (Manifold Absolute Pressure Sensor), which is on the front left of the engine near the idler pulley mounted by a single fastener to a bracket from the water pump. It has a vacuum line or two and an electrical connector going to it.

Check it very carefully, the lines get brittle and crack, sometimes it is hit during maintenance and a line falls off or a nipple on it breaks (it can also be damaged if the idler pulley fails and the belt whacks it). It's easy to change and not terribly expensive, either.

I'll see if I can find a pic of it in situ to post to help you find it.

Here's the pic; unfortunately it won't embed full-size, so you'll have to click it to view it properly. The MAP sensor is circled in red.

Note that the engine cover has been removed in this pic, which you'd want to do for a proper inspection.

Incidentally, WD-40 isn't the best product to check for vacuum leaks. ;)

Attachment 128673

talked to the guys at pelican this morning and ordered some diesel return line to replace the old vacuum hose, he said sensor rarely go bad

I didn't mean you should just plan on replacing it.

But if you ordered the hose then you examined it and determined the hose was shot? It doesn't have to be anything fancy, regular vacuum line will be more than sufficient, any auto parts store has that and no shipping charge either. ;)

But if you haven't examined it, that would be the first step. I've seen a few of them with the nipple broken off, and maybe the sensor itself is still good, but that indicates replacement. Perhaps if you were to superglue the nipple back on and then build up around it with some J.B. Weld to reinforce it that might work.

Still, the first step would be to inspect the thing. And trace the vacuum line back (I think it goes to a port on the manifold edge IIRC) and make sure the line is attached.

Good luck.

finally got around to fixing it , changed the 2 vac hoses since I was there and both were rotted, no more codes, the parts guy recemended using the old diesel fuel return lines, it's the same size but has the braid cover, I used it years ago ago on my 300 d and other stuff but had forgotten about it, bought a bunch and plan on replacing all my lines as needed