P0106 in the middle of summer - Page 3 - Chevy and GMC Duramax Diesel Forum
07.5-10 LMM Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #21 of 32 (permalink) Old 09-03-2019, 08:59 AM
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There seems to be some confusion on this topic so I thought I'd do some looking into it.

I have an LMM so I went out and looked in the usual locations for a BARO sensor. It isn't there. The bracket that the two main engine wiring harness connectors mount to also has the tab that would mount the BARO sensor as used on some earlier engines but it wasn't there. I also didn't find it under the coolant hose like some older engines had.

I googled "LMM BARO sensor location". Guess where it sent me? Right here to the DF.

I also looked on RockAuto for a BARO sensor for an LMM. I couldn't find one but when I entered BAROmetric pressure sensor it took me to the listing for the MAP. One of the listed MAP sensors suggested that it could also be used as a BARO. Such statements are not reliable though.

I have checked through Alldata. There is nothing in the parts locating area. There isn't a mention of it in the wiring diagrams. It isn't listed as a separate sensor in any of the 4 locations I checked. The ECM description is pretty skimpy but it also doesn't mention the BARO sensor. I went through several DTC descriptions and the only thing I found was a mention under P0106 that the MAP and BARO have to match at startup within 14 kPa, which is 2 psi, or the code will set but it is normal to only have 5kPa difference.

I did find a DTC for the BARO itself. It is P2228/P2229. In the description of that code it says that the BARO sensor is part of the ecm. That means it doesn't see any vacuum/pressure changes other than atmospheric and can not see any air flow. Let's hope no one has to replace the BARO because being part of the ECM it will be way too expensive.

The MAP sensor is located in the hot side pipe so it sees pressure changes but it does not sense flow. Flow is only sensed by the MAF.

My scanner will read both MAP and BARO while the key is on but the engine is stopped (KOEO). For those having trouble doing this it may be a problem with the scanner they are using or maybe they need to do something like MIkey52 suggested.

There are some diesel engined vehicles that use an intake flap which creates some vacuum. Mercedes does this a lot. I have one. That is unusual though. Mostly the cause of vacuum in the intake of a diesel is due to a restriction. Of course the most common restriction is a dirty air filter but it cold also be a collapsed hose or something else. Normally the MAP and BARO should be nearly identical KOEO and KOER at idle. The turbo produces a tiny amount of boost at idle which just about compensates for the restriction in the air filter so that the MAP and BARO remain the same. As engine speed increases so does exhaust flow so the turbo spools up. As the turbos becomes more effective and starts to make real boost. That is why the MAP reading goes up.

The BARO should only change with altitude or big changes in the weather. Many vehicles actually take a snap reading of the MAP at start-up and use that for BARO for the rest of the trip. Ours don't do this but many vehicles do.

We also have an air temp sensor (IAT). BARO and IAT combine to give a close estimate of atmospheric air density. If there was also a sensor for humidity then it would be even more accurate but so far we don't have to have one of those. The MAP sensor is there primarily to tell the ECM how the turbo is doing. The turbo bumps atmospheric pressure up. The result is manifold pressure which is what the MAP is all about. A few engines have a second temp sensor in the intake and after the intercooler. As far as I can tell we don't have that either but it would tell the ECM how well the intercooler was working.

I know that what I have posted here disagrees with what some others have said. Chose to believe what you like. I just wanted to present the facts for your consideration.
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post #22 of 32 (permalink) Old 09-03-2019, 06:14 PM
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Great research mizterwizard. Too bad ALLDATADIY.COM doesn't have a device specific advisory about the BARO sensor, like they do about the MAP, MAF, etc. I knew it had to be somewhere!
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post #23 of 32 (permalink) Old 09-04-2019, 08:39 AM
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Quote:
Originally Posted by MIkey52 View Post
D R C

Next time in your truck, key on engine off, touch the screen of your cts2 and it should come to life.
, Ya I didn't think about that and yes I have the same readings key on engine not running BARO 13.8 MAP (which I do know what the abbreviations mean) 14. The same with the engine running.

Now back to my original suggestion how about starting the engine to see if the numbers increase and get close to each other.
If they do Then that could be a sign of something electrical going on or even a bad sensor wherever it gets its signal from.
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post #24 of 32 (permalink) Old 09-04-2019, 10:48 AM
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Originally Posted by D_R_C View Post
, Ya I didn't think about that and yes I have the same readings key on engine not running BARO 13.8 MAP (which I do know what the abbreviations mean) 14. The same with the engine running.

Now back to my original suggestion how about starting the engine to see if the numbers increase and get close to each other.
If they do Then that could be a sign of something electrical going on or even a bad sensor wherever it gets its signal from.
Good idea. That is always a good test. When something is acting up it is a good idea to try different situations to see if things change or stay the same. That can tell you a lot about what the problem is.

In this case the BARO should not change at all but the MAP should change a little, perhaps not enough to register but if it does register then a small change is acceptable. If the BARO changes at all it could indicate wiring or an ECM problem (since the sensor is part of the ECM). Let's hope for wiring because it is cheaper to fix. On the other hand it is harder to find wiring problems.
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post #25 of 32 (permalink) Old 09-04-2019, 07:01 PM
 
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I had some time to work on the truck tonight and did a little testing beforehand on the sensor pigtails, here's the results;
MAF; Engine off key off - Second and fourth pin looking down from left to right have continuity to ground and noe of the pins show voltage. Engine off key on - pin 1 4.97 volts, pin 2 nada, pin 3 11,57 volts, pin 4 nada, and pin 5 4.95 volts. All seems normal.
MAP Engine off key on - pin 1 4.97 volts, pin 2 nada, pin 3 continuity to ground. Again this seem normal. Still the Torque showed less than 8 pounds baro and this just ain't right.
Both batteries measured 12.2 volts at rest. I checked the wiring harnesses again but found nothing amiss. I swapped out the Delco MAP sensor for another cleaned used one and cleaned my Delphi MAF sensor with Map sensor cleaner. The truck now shows 12.9 baro at idle and a 0.9 negative boost at idle. It I goosed the throttle up to about 2K the boost would show a pound or two, the baro would go up to close to atmosphere, and the Banks A pillar gauge would show a little bit of boost (< the 2 pounds it starts at). This too all seem fairly normal.
The only problem is that I have been through this procedure more than a dozen times before and I know that it will again go to low baro and kick out a your basically F'd "engine Power reduced". This is why I am trying to find out how a LMM reads boost. From what I've been able to find baro could be read by either a combo MAF sensor or by the ECM. Ron one of your great posts makes me believe that an intermittent glitch in the ECM may be the culprit. Now do I have to replace it? or can it just be re-flashed? or am I barking up the wrong tree entirely??
Thanks for all the posts guys, somewhere in them there is bound to be one little tidbit that will unlock this vexing mystery.

2008 GMC 2500hd SLT. LMM with Banks Economind tuner.
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post #26 of 32 (permalink) Old 09-04-2019, 07:07 PM
 
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Oh, by the way, I live at about 1100 feet elevation so the baro would read a little low, 10% maybe?? Also as per Mizterwizards post I have seen a P0229 a few times when the beast is acting up ...and also sometimes a P0101 to go along with it. The code are like a road sign pointing to the same town in two different directions and that kinda leads me to believe that the culprit lives in the ECM

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post #27 of 32 (permalink) Old 09-04-2019, 09:01 PM
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Even though the batteries are measuring good, how old are they? I ask because I've seen a ton of issues as of late be resolved by replacing the batteries. Some tested well as well but they turned out to have internal issues that were not showing up when tested with a meter. I really hope you are able to get this resolved.

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post #28 of 32 (permalink) Old 09-05-2019, 09:55 AM
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Here is a picture of the MAF connector showing the connections:
MAF.gif

Here is the MAP connector showing the connections:
MAP.gif

And the BARO as discussed is contained within the ECM so no connector there.

I am concerned with the state of charge of the batteries when not running. They should be in the 12.6 - 12.7 range, not 12.2. Yes, they 12.2 batteries will likely start the truck reliably, but they're way undercharged, approx 60%


With key on, engine off, none of the B+ connections should be higher than 12.2 with your batteries. With engine running and alternator supplying voltage, it should be very close to the voltage output of the alternator.

The BARO only shows atmospheric pressure. If the atmospheric pressure where you are goes up, the BARO reading should go up and if atmospheric pressure goes down, the BARO reading should go down. Of course, it you go up a big mountain, the BARO will fall accordingly because atmospheric pressure is less at high altitudes. This appears to be where your problem is, as far as I can tell. But before I changed ECM's, I would change my batteries, clean both ends of all of the battery cables, BOTH ENDS, and also the alternator cable.

MAP shows pressure (or could be negative) inside the intake system which will reflect any boost produced by the turbocharger. This is where your ECM gets it's boost pressure.

So, BARO = Atmospheric pressure (baseline pressure)
MAP = Boost
MAF = Airflow

Sometimes electrical devices will work quite well with a range of voltage inputs, sometimes they won't. Charge your batteries so that after an overnight rest they are fully charged. Then do your BARO test. I don't think that a reflash of the ECM will correct the BARO reading problem, it will take a new ECM and a complete flash with most current updates. Another POSSIBLIITY is to contact a place that revuilds ECM's and see if they can just repair the BARO portion of your existing ECM.

------------------------------------------------------------------------------------------------------------------------------------------------------
Here is info on P2228:


DTC P2228 or P2229

Diagnostic Instructions


  • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
  • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
  • Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors

DTC P2228

  • Barometric Pressure (BARO) Sensor Circuit Low Voltage
DTC P2229

  • Barometric Pressure (BARO) Sensor Circuit High Voltage
Circuit/System Description

The barometric pressure (BARO) sensor measures the pressure of the atmosphere. This pressure is affected by altitude and weather conditions. A diaphragm within the BARO sensor is displaced by the pressure changes that occur from varying altitudes and weather conditions. The sensor translates this action into electrical resistance. The BARO sensor wiring includes 3 circuits. The BARO sensor and all related circuits are inside the engine control module (ECM). The BARO sensor provides a signal voltage to the ECM, relative to the pressure changes on the BARO sensor signal circuit. The ECM converts the signal voltage input to a pressure value. Changes in BARO due to weather are relatively small, while changes due to altitude are significant. Pressure can range from 56 kPa at an altitude of 4 267 meters (14,000 feet), to 105 kPa at or below sea level. The BARO sensor has a range of 8-207 kPa. The ECM uses the BARO sensor input for fuel delivery and other diagnostics.

Conditions for Running the DTC


  • DTC P0652 or P0653 are not set.
  • The ignition is ON.
  • DTC P2228 and P2229 run continuously when the above conditions are met.
Conditions for Setting the DTC

P2228

The BARO is less than 60 kPa for 1 second.

P2229

The BARO is more than 120 kPa for 1 second.

Actions Taken When the DTC Sets

DTCs P2228 and P2229 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P2228 and P2229 are Type B DTCs.

Circuit/System Verification

Important: If you cannot duplicate the condition, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.


  1. Turn ON the ignition with the engine OFF.
  2. Observe the BARO parameter with a scan tool.
  3. Compare the BARO value to the range specified in the altitude vs. barometric pressure table.
    • The BARO parameter should be within the range specified in the altitude vs. barometric pressure table.
  1. Engine running, observe the DTC information with a scan tool. DTCs P2228 or P2229 should not set.
  2. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing


  1. Turn ON the ignition, with the engine OFF.
  2. Observe the BARO parameter with a scan tool.
  3. Compare the BARO parameter to the range specified in the altitude vs. barometric pressure table.
    • If the BARO parameter is outside the range specified, replace the ECM.

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post #29 of 32 (permalink) Old 09-05-2019, 02:47 PM
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Ron got back to you before I could and he has the same info I was referring to so you should be all set.

One thing, there is no P0228 or P0229. The appropriate codes are P2228 and P2229 which indicate that the BARO is unreasonably high or low.

As Ron highlighted, the only cure for a bad BARO is to replace the ECM. That means a trip to the dealer to get it programmed as well. Not good news but at least there is a path to repair ahead.

The P0101 code indicates MAF performance problems but if the BARO is wonky then that could lead to the P0101 code. It could also mean that the ECM is not reading the MAF correctly even though it is a good signal.

The diagnostic that Ron posted refers to codes P0652 and P0653. Those are for high or low 5V reference problems. You haven't said that you get these codes so they really don't matter but if you had them they would also point to the ECM since it makes the 5V reference to begin with but they could also point to shorts to power or ground.

It looks like you are headed for an ECM replacement but before I went to that expense I'd probably check all of the 5V reference wires for a short to ground. It is possible for there to be just enough of a drop in the reference voltage to mess with the BARO but not enough to set the code. It's not likely and I wouldn't worry about it except for the high cost of replacing the ECM.
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post #30 of 32 (permalink) Old 09-07-2019, 11:57 AM
 
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Hi guys, thanks for all the great well thought out responses. The notes that the batteries are due for replacement are indeed correct and I'll be doing that shortly because it is now fall and the now temps regularly falling to less than 60 by morning. THe truck starts fine at the moment and I'm just waiting the Fall sales on batteries to commence ...it's the frugal old yankee in me coming out.
I don't think the weak batteries are the issue however because often as not the engine goes into limp when the truck has been running for a while and the voltage very quickly jumps up to the normal 14.5 volt float stage. The 12.2 mentioned in the last note was after the truck had been sitting outside unused for about a week.
I'm fairly certain that it is the baro discrepancy and suspect that a ECM replacement may be needed. Here is what has occurred over the past week, please do share your insights based on this. I cleaned the MAF and installed my cleaned spare MAP after the last bout of P01016 codes causing the truck to go into limp. The truck ran normally again and no codes popped during a short test drive. At idle, when the truck normally will act up, the Banks boost gauge would read zero, but the Torque Pro would show 12.9 psi, a negative 1.2 boost, and a 160 cfm MAF reading. While driving down the road and running normal boost levels the Banks guage seems to consistently read a pound or two higher than the Torque Pro at the same time. Its hard to really verify this for I'm instantaneously trying to read two gauges while at the same time driving. I doubt that the Banks gauge has any bearing on engine performance, but maybe the sensor I installed in the exhaust does?? This also might possibly be the culprit causing the low baro readings??
Set the Banks controller to zero (out of 5) gain positions and towed my excavator about 50 miles without issue. I have learned to use the no gain setting when towing after having the intercooler hose clamp break and the hose blow off (POW!) while running roughly 25 pounds of boost while towing 11K of excavator and trailer up a long hill. Since getting into this habit I also try to modulate the throttle a bit to ensure that the boost on the Banks gauge shows less than 20 pounds. Central NH is very hilly and it is not unusual to see the pyro gauge reading between 12-1300 when running at boost for any length of time so I monitor than as well and keep it below redline. While idling midtrip at a stop light the MAP and boost figures would be about the same but the MAF dropped to 112. A reading difference due to the heated manifolds perhaps?? The truck was running perfectly at this point.
I started the truck at the end of the day and was backing it up to drop off the dump trailer when it agin went into limp. At this point it threw both P0101 and P0106 codes. I had to clear the codes twice in the first two miles but I could also tell by the exhaust note that a regen cycle had started. Sure enough within a minute the f'ing "clean exhaust filter nanny started bonging and took over the DIC and any information I might have been able to get from that was lost. I HATE the reduced engine and nannies that take over this truck and wish I had just deleted everything and gone with a different programmer! NH isn't a tail pipe state, but I had gone with the Banks because I had thought that if I traded it or sold it a full delete would have hurt the resale badly. Anyway, it hasn't been unusual for the last couple of years for the truck to throw both 0101 and 0106 codes when going into regen. Another piculiarity is the the Banks boost gauge will jump up to 40 ponds and stay there, but the truck is running normally (for regen) and the Torque tells me that the boost is also in a normal range. I drove forty miles home and the regen kicked out after about 25. Just before shutting it down when home I checked again and the Torque showed 12.9 psi and a -1.2 boost at idle. Stopping the motor but not turning the key off showed the same 12.9 baro.
I still think the problem is the baro pressure. My next step will be to go to someone with a proper OBD reader and verify that the Torque Pro is reading correctly. Next I will install new batteries, they are definitely due but I don't believe they will make any difference. If the problem still exists after the battery change I guess it would make sense to swap out the ECM. Finally if the problem still exists I guess I will need to somehow disable or totally remove the Banks Economind. Would you agree with this plan?
Hopefully the codes set during the initiation of regen will also be related to the low baro base too and not be another wholely different problem. FYI, the regens seem to occur every 250-350 miles, depending on how heavily loaded I'm running.
One more thing for those of you with Banks Econominds that may have witnessed the same false 40 pound boost gauge reading. I find that the needle won't drop to zero until I tap sharply on the gauge housing, it will then drop to 0 and read normally. Stiction on the gauge needle at the upper end of the meter perhaps??
Thanks in advance for any input to this vexing problem! Hopefully the insights will be valuable to more than just me.
Peter

2008 GMC 2500hd SLT. LMM with Banks Economind tuner.
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