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Discussion Starter #1
1999 E320 W210 base, 149K miles. Check engine light has been on for several months. In April I got a new transmission but the check engine light came on after a few days. Scanned it yesterday and P0105 came up: maybe Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction? Or 02 sensor Bank 2 sensor 1 (which was one of the codes along with P0130, P0135, P0155 that appeared when a mechanic scanned before I changed the transmission.

I asked a rep at Advance Auto parts what P0105 means, he said it could be caused by several things including MAP and faulty 02 sensors. Then I read online that a bad MAP/Barometric it would make the car run rough, but it has run great ever since the new tran was installed

P0150 code came up last year with others that no longer appear (P0130, P0135, P0155). Installing the new tran seemed to fix everything except P0150. Last year - i.e. before new tran, the mechanic wanted to charge an arm and a leg to install 4 new Bosch sensors.

I have been driving only 10-20 miles a day since I got the new tran. In a few days I will go on a trip that will cover about 300 miles with temps in the mid 90s. About 120 miles at a time - and back a few days later.

How many drive cycles would be needed for the light to reappear?
Could faulty 02 Bank 2 Sensor 1 be it.... and be serious?
Am I taking any risks by driving 300 miles over 3 days?
Any good advice is much appreciated :smile
 

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P0105 refers to MAP sensor. I'd check to see if the vacuum tube that goes to the MAP sensor is intact before replacing it. I almost never see them go bad, only the vacuum tube.



That's the map sensor. There's a tube behind that. If the tube looks cracked, stretched or has holes, that vacuum tube needs to be replaced. Stupid easy to do. Parts store charge $1 per foot. You only need 6 inches or so.

And no, you won't damage anything by driving 300 miles on that code.

Typically 2-3 drive cycles, and by drive cycle I mean from two cold starts consecutively. Starting the car first thing in the morning, then going for 10 miles trip, going to grocery store for 30 minutes and going back home -- thats 1 drive cycle, even though you started the car twice.

Starting the car first thing in morning, going on a 10 miles trip, going to work, then shutdown the car. 8 hours later you come out and start the car to go home? That's 2 drive cycle, because the engine cooled down completely to ambient temp.
 

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Apart from the vacuum leak, it could also be a wiring / connector issue. I would just look at the barometric pressure values on the scanner live data, when the ignition switch is in position 2 (engine off), then start the engine and read the value, and pres the gas pedal to observe changes. If no change, it is likely an electrical / component problem.

MB uses MAP mainly for EGR performance monitoring, not for air/fuel ratio control. It uses the MAF for that. Some cars do not have a MAF and rely on the MAP sensor for air/fuel ratio control (like my 2003 Honda Accord). In those cases, a bad MAP certainly affects the engine performance and running.

If the MAP vacuum hose has a small leak (cracked hose), typically this will not cause a MAP fault. but you would have EGR faults (P0400), as MAP will not register the vacuum change properly when the EGR is being activated during the test.
 

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Also for the O2 sensor issues, it appears that the two pre-TWC (Catalyst) sensors had heater faults at the same time, plus sensor fault from one of them. It is unlikely that you have two heater faults at the same time, so it is likely that that you had a wiring issue (an intermittent open that supplies power to the sensors maybe) which was resolved, at least temporarily when the transmission was changed.

Hard sensor heater faults are not known to heal themselves:)

You can of course monitor the output from the O2 sensors if your scanner supports graphing.
 

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Discussion Starter #5
Thanks both of you for your advice. Rescanned it today. I missed two codes yesterday, P0400 and P0410. That's too many issues for me right now. I'm getting the tires rotated and oil changed at my fave shop. Will have them scan and advise.
 

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Discussion Starter #6
The culprit is "excessive carbon buildup" throughout the engine. The shop said not dangerous to drive but they can't clean it. Suggested going to MB dealer to see what they could do. Also said engine might need to be rebuilt. I used Seafoam about 3 weeks ago. Evidently that's not enough to clean it out.
 

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How did the shop come up with the "excessive carbon buildup" diagnosis?

You have a P0150 code, NOT a P0105 code as you (may have mistakenly) written a few times, right?

I had a pending P0150 code on my 1999 E320 with approx. 72k miles. When I cleared it, it would always come back--but always as a "pending" and not a "confirmed" code. A few months back, my car stalled while at a stop and had trouble starting afterwards. Based on that one instance, I changed the crank position sensor (as I had the part ready, waiting for the day). Well, I really can't say if the new CPS "fixed" my stall and restarting problem--as it had only happened that one time--but I have not had an repeat instances of it since then. However, a surprising byproduct of the new CPS is that I never got the P0150 code back after clearing it when I installed the new CPS.

When I checked the P0150 code info, I found it was related to heater issue on the bank 2 pre-cat O2 sensor. When I checked the resistance across the two white wires going to that O2 sensor, I got a reading of 3.1 ohms. When I checked another O2 sensor, I got a reading of 2.1 ohms. Not sure if the resistance difference caused a sufficient decrease in heat generation on the O2 sensor to create problems or not. But my hypothesis is that maybe a marginal O2 sensor with heater circuit issue, coupled with intermittent issue with the CPS, triggered the P0105 code in my case. I see another issue with my bank 2 pre-cat O2 sensor using my OBD II scanner right now, and am planning to replace that sensor soon, although I do not have any error codes or noticeable performance issue--other than slightly low gas mileage.

EDIT: I had both P0150 and P0155 codes--both pending and not confirmed. The P0155 code was the heater circuit code for pre-cat bank 2 O2 sensor. The P0150 code was for voltage limit issues with the same O2 sensor. On my OBDII reader (bluetooth connection to cell phone app), I can see that the voltage range on that sensor is indeed in a narrower range (~0.35V to ~0.65V) than it should be, intermittently; that's why I'm planning to change this sensor.
 

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Discussion Starter #10
andrewSF - thanks for your interest. P0150 and P155 were codes from last year. Last summer I changed one of the 02 sensors under the hood near the firewall so that might have fixed them. Here are photos of mechanic's reports from July 20. The work is suggested, not completed. As you can see they think it's a mess, or - as MrBoca said -"They do not really have a clue on what is going on"
 

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Just check / fix the vacuum hose and the electrical connection as in Post #2. It may solve your P0400 and P0105 issues.
 

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Discussion Starter #12
Looked closer. Wires and tubes are OK but saw the right side air inject shutoff valve. The metal stem broke above the the nut or screw that holds it down (shop missed it. I can get one for $143 from mercedespartshub.com. Is $60-$70 less than what other merchants charge but I'm not sure how to install it. Do I remove...manifold?

I should probably replace the tubes as well - they are pretty dried out.
 

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Here you go :) just invest in some E-torx socket set, and remove the bolt. The base and the pipe stub should come out with some persuasion. So hopefully that should take care of your P0410 at least, and possibly other issues as this would like a leak in the exhaust side.

Look at the picture of the item you will order and you will see what is left in the mounting location. Clean the location while you are there :)

The part you need is the lower part, as it is broken. It would be an idea to get a used part for about $40, and change the bottom part out.
 

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Discussion Starter #14
I will try. Where would I get a used bottom part for a 99 MB? The only dealer of OEM parts left my area 2 years ago. There are only new complete air inject shutoff valves at Amazon and they cost $215-220. Thanks
 

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Great :) too bad they do not sell the stem part separately, but sell the valve top. I guess it does not get broken often :)
 

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Discussion Starter #20 (Edited)
What can I use to extract the broken pipe stub from the port? Need grab the stub from inside the hole. It's flush, nothing sticking out that can be grabbed or tapped. I found these vids but the stub doesn't have threads.
 
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