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Discussion Starter #1
So I'm at my wits end, I have been working on this same code for two weeks now its: P0101 Mass airflow performance. I tried cleaning the sensor with maf cleaner, replaced the air filter, made sure all the clamps were tight then went and drove some miles to check for codes. The light came on around 55 miles, so since I didn't see any boost leaks or any other issues, I assumed I needed to replace it, I bought a new sensor and drove about 100 miles and no light.. Good news right? Well when I pulled it in to the smog station (thanks to living in commefornia) the light came back on 馃槧. I don't know what else to do.. Does anyone have suggestions for where to look or what to test?
 

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A lot of treads with people having a this code they have traced it back to either fuel pressure regulator or egr system you should search the code on here and see what you come up with. There seem to be a good amount of treads with this code.


02ecsb lb7/zf6 284k
Stock intake pro fab intake horn
Stock exaust ppe boost valve
P0102 code that I can't get rid off
Efi live not on the truck yet
 

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All right, so looking in your sig, you have some minor mods done. So, how of your list... did you add anything new in the last month?

Now if you haven't, I would check the sensor wires and check to see if anything is chaffed. That code also signals if you have lost communication to the ECU, even for a split second.

Now if that checks out, check your boost valve and programmer. If you create an over boost situation, the computer flips out and will set the code. Basically you are looking to eliminate items that are easy to get to first and take them out of the loop.

If all of that checks out; living in Cali, I am assuming you have an EGR and all that fun stuff. The EGR along with the emissions equipment communicate with each other. SO if your EGR is stuck or so dirty that the flow is compromised, it can trigger a MAF code and not necessarily a P0401 EGR Flow Insuff code.

So check those out and report back.
 

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Discussion Starter #4
A lot of treads with people having a this code they have traced it back to either fuel pressure regulator or egr system you should search the code on here and see what you come up with. There seem to be a good amount of treads with this code.


02ecsb lb7/zf6 284k
Stock intake pro fab intake horn
Stock exaust ppe boost valve
P0102 code that I can't get rid off
Efi live not on the truck yet
My mistake, i meant to mention that i have been searching these forums as well for the last two weeks. I read almost every single thread I could find on the P0101 and a lot of different things were mentioned, the egr was one of them, but I never actually saw a solution to the problem if it actually was the egr?




All right, so looking in your sig, you have some minor mods done. So, how of your list... did you add anything new in the last month?

Now if you haven't, I would check the sensor wires and check to see if anything is chaffed. That code also signals if you have lost communication to the ECU, even for a split second.

Now if that checks out, check your boost valve and programmer. If you create an over boost situation, the computer flips out and will set the code. Basically you are looking to eliminate items that are easy to get to first and take them out of the loop.

If all of that checks out; living in Cali, I am assuming you have an EGR and all that fun stuff. The EGR along with the emissions equipment communicate with each other. SO if your EGR is stuck or so dirty that the flow is compromised, it can trigger a MAF code and not necessarily a P0401 EGR Flow Insuff code.

So check those out and report back.
So I should have been a bit more thorough on my last post, I realized I left some stuff out when I wrote this last night.

1. I have had this code on and off since I bought the truck two years ago, but now that smog is due, that's is the reason I'm actually fixing it now. It never bothered me in the past because it did not effect performance at all and would only come on for an hour or two and then be gone for a 1 week - month, then it would repeat and go away. . so it was never that big of an issue.

2. All performance mods have been put back to stock for the smog. No exhaust, or tuner, the only thing on the truck still is the boost valve, but since I have had the p0101 since long before the boost valve I don't think its that.

3. Yep I have the stupid egr and cat, etc. . . so I'm thinking that's where I need to start looking next. The wires seem to be good on the sensor itself so that really narrows it down to that egr.. Any ideas on how to check that?


-Thanks for the responses!
 

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We'll just recheck the wire and make sure to follow it all the way to the harness.

As for the EGR, you will have to take it apart and check the ports for excessive carbon build up. You'll need to get some carb cleaner and a long bottle cleaning brush and scrub down the tubes; that's if it is clogged. But doesn't hurt to do it anyways. As far as the egr itself. Look at the valve. Sometimes you can get the working again by cleaning then out. But a dead valve is a dead valve. I personally haven't found a great way to check for a dead valve. Some say to shake it, if it rattles, it's no good. But I've taken some out and shook em and they rattle right out of the box. The only thing I have found to work for an egr was to just replace it. I feel that if the part is original and an egr may be at fault, it probably served its purpose. You have it out anyways, replace it. I'm not the one that likes to chuck parts at something, but I do like to replace parts if I feel they are close to their service life.

So hopefully this helps.


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Discussion Starter #6
We'll just recheck the wire and make sure to follow it all the way to the harness.

As for the EGR, you will have to take it apart and check the ports for excessive carbon build up. You'll need to get some carb cleaner and a long bottle cleaning brush and scrub down the tubes; that's if it is clogged. But doesn't hurt to do it anyways. As far as the egr itself. Look at the valve. Sometimes you can get the working again by cleaning then out. But a dead valve is a dead valve. I personally haven't found a great way to check for a dead valve. Some say to shake it, if it rattles, it's no good. But I've taken some out and shook em and they rattle right out of the box. The only thing I have found to work for an egr was to just replace it. I feel that if the part is original and an egr may be at fault, it probably served its purpose. You have it out anyways, replace it. I'm not the one that likes to chuck parts at something, but I do like to replace parts if I feel they are close to their service life.

So hopefully this helps.


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Will do, I'll check the wires as far as I can and then start messing with the egr. Any recommendations on where to buy the egr parts if needed?
 

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Where ever you can get the cheapest GM part. I say GM because this is going to be something you don't want to tear into for a while. Aftermarkets parts are great for easier jobs. Just as some suspension components or interior stuff, just things that are not critical. Sensors, valves, and electronic units are best left to GM, Delphi, or AC. I've seen a lot of aftermarket sensors and such not to so well in real world situations. SO find the part number online and find the cheapest OE part that you can.
 

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Discussion Starter #8
Will do, thanks again! I'll update after I have gone through everything.
 

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Here is the information for a 2003, that will give you some help in testing the P0101.


Larry
 

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Discussion Starter #10
Here is the information for a 2003, that will give you some help in testing the P0101.


Larry
Thank you very much! I was just reading through that PDF and I noticed that its supposed to read 42-50 g/s at idle and I see 29 at idle, that is with a new MAF sensor. Can you guys confirm that is the correct number?
 

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Sorry, I can't confirm those numbers, as I don't wrench on the Duramax. Maybe someone
else can give you that confirmation.

Does your OLD MAF sensor read the same as the new one at idle?

That troubleshooting procedure also talks abut the Throttle Position Sensor and the Barro sensor could cause problems.

Are you sure there aren't more codes?


Larry
 

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Discussion Starter #12
Sorry, I can't confirm those numbers, as I don't wrench on the Duramax. Maybe someone
else can give you that confirmation.

Does your OLD MAF sensor read the same as the new one at idle?

That troubleshooting procedure also talks abut the Throttle Position Sensor and the Barro sensor could cause problems.

Are you sure there aren't more codes?


Larry
Yep, I'm positive there aren't any other codes. And yes the old and new sensors read the same. It seems like the old one may have read about 26-27 g/s and the new one is about 29-30.. That's the only real difference, and that may have something to do with the new air filter? I'm not sure. I'll go through the whole list this evening and hopefully I can come up with something. Thanks again for your help!

If anyone has any info on the g/s information that would be much appreciated as well!
 

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Discussion Starter #13
So after a long weekend of searching, cleaning and trying to diagnose the issue I am still getting the code. Things I did to try and fix the problem were: Checked the Barometric sensor, It was reading 14.7 PSI which from what I can tell is the correct number. I checked the boost pressure sensor, and that was reading correctly as well. The MAF was reading at about 29-30 G/S at idle when its warmed up, that is the only thing that looked a little odd, I read that it should be at 40-50 G/S, so that is the only thing that doesn't add up (anyone have info on this?) I checked the ENTIRE air system for leaks and found nothing. And lastly I checked and cleaned the entire EGR system. I'm not sure what to do, I am at the point that I am going to take it to the shop to have it diagnosed, I'm thinking that there may be a flash update for the ECM..? Thanks again to all those that helped!
 

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Well I just went and hooked up the scanner to mine to see what it reads to get a comparison and mine reads a constant 0 on the maf. lol. So I don't have any insight for you sorry.
 

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Where are you located in Cali
 

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Discussion Starter #16
Where are you located in Cali
Im in the east bay area, Concord to be exact. And that's strange that you are getting a 0 reading, lol is your scanner is working properly?
 

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I hope so lol it's a snap on solus. I have another one that I'm gonna try right after dinner. Did you check for 5volts and all the grounds are good?. There are a few grounds on each side of the engine block and when I got my truck a couple of them were broken off.
 

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Ok so I just hooked up my other scanner and it is reading 37-41gs. So the snap on one isn't picking it up... That's weird being that it is 20 times the cost of the OTC one I have lol
 

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im pretty sure the maf sensor should read high 40's gps at idle I can check tomorrow, if you go to https://tis2web.service.gm.com/tis2web and put your vin in it will give you the current calibration id then you look at your ecm with the scanner and compare. when you checked for leaks air leaks did you make the pcv tools to block off the pipes and pressurize with shop air (regulated)? also un bolt the harness connectors on the driver side 5mm allen head turn over and look for rubbed wires
 

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Discussion Starter #20
I hope so lol it's a snap on solus. I have another one that I'm gonna try right after dinner. Did you check for 5volts and all the grounds are good?. There are a few grounds on each side of the engine block and when I got my truck a couple of them were broken off.






Ok so I just hooked up my other scanner and it is reading 37-41gs. So the snap on one isn't picking it up... That's weird being that it is 20 times the cost of the OTC one I have lol

Ok so I am reading low for sure. I'm not sure how to check for voltage, I have a meter, what is the best way to check that? I'll double check the grounds. I didn't find anything when i was looking but I could have missed something.




im pretty sure the maf sensor should read high 40's gps at idle I can check tomorrow, if you go to https://tis2web.service.gm.com/tis2web and put your vin in it will give you the current calibration id then you look at your ecm with the scanner and compare. when you checked for leaks air leaks did you make the pcv tools to block off the pipes and pressurize with shop air (regulated)? also un bolt the harness connectors on the driver side 5mm allen head turn over and look for rubbed wires
I didn't actually put pressure to the system. Is there a "how-to" on the pvc tools? That would be helpful. It was more of a very detailed visual inspection. It may be a good idea to pressurize the while system.
 
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