PO101 and PO171 engine codes

Hey guys, Im new here, so I hope this is the right place to post this question.

I've been noticing my truck hasn't been running right. My check engine light came on so I took it to Advance Auto parts to let them read it.
2 codes came up

PO101 and PO171
I got on here and notice it was something to do with the Mass Air Flow. Can anybody suggest a reason to fix this.
Thanks guys

my truck is a 2007 WT Silverado.

oh and would this fit under the powertrain waranty?

Hey guys, Im new here, so I hope this is the right place to post this question.

I've been noticing my truck hasn't been running right. My check engine light came on so I took it to Advance Auto parts to let them read it.
2 codes came up

PO101 and PO171
I got on here and notice it was something to do with the Mass Air Flow. Can anybody suggest a reason to fix this.
Thanks guys

my truck is a 2007 WT Silverado.

oh and would this fit under the powertrain waranty?

What engine?
What mileage?

Power train is transmission and engine and rear ends and or transfer case..
Check with your GM dealer on other stuff that is under warranty.
Some stuff is covered under the federal emission warranty.
Let us know what you find there.

As for fixing codes scanner reading should be checked out and codes should be cleared and see what comes back.
Any add on air take stuff?

If code does come back you need to go threw the repair flow chart for that coder.
Is it all hooked up good?

Or you just asking for a reason to fix it or how to fix it?

What engine?
What mileage?

Power train is transmission and engine and rear ends and or transfer case..
Check with your GM dealer on other stuff that is under warranty.
Some stuff is covered under the federal emission warranty.
Let us know what you find there.

As for fixing codes scanner reading should be checked out and codes should be cleared and see what comes back.
Any add on air take stuff?

If code does come back you need to go threw the repair flow chart for that coder.
Is it all hooked up good?


Sorry,
its an V8 4.8 Vortec with about 33,000 miles
Its complete stock, I erased the codes just a few minutues ago, so we'll see what will come back

Thanks again!!

Or you just asking for a reason to fix it or how to fix it?


..asking how to fix it.

Is it a mass air flow sensor needing replaced. or could it be anything?

Here are what the codes read:
PO101- MAF or VAF A CKT Range/perf

PO171- System to lean (Bank 1)

and when I hooked the scanner up the second time it said the code number and then PD

I looked what PD stood for and it said Pending Codes are also reffered to as "continous monitor codes" and "muturing codes". Pending codes occur when the code has not occured a specific number of times, causing the code to mature.

..asking how to fix it.

Is it a mass air flow sensor needing replaced. or could it be anything?

Here are what the codes read:
PO101- MAF or VAF A CKT Range/perf

PO171- System to lean (Bank 1)

and when I hooked the scanner up the second time it said the code number and then PD

I looked what PD stood for and it said Pending Codes are also reffered to as "continous monitor codes" and "muturing codes". Pending codes occur when the code has not occured a specific number of times, causing the code to mature.

With a hard code the check engine light should be on.
Pending code is a code getting ready to set because of the problem there.
History or past codes are code that have set and cleared up.

As said clear code and drive and watch for what comes back .
if any do post back codes no.

And call dealer and check on your warranty on it.
Let us know what the dealer says.

Another note. Today when I was leaving for work I notice the truck wasn't idling right, it kept trying to die. So put it in drive and it act like it wasn't getting any gas. It wouldn't go with my foot all the way down on the pedal. Now it seems like it's a fuel pump. But how can that be with the code said MAF. Any ideas what could be wrong

Another note. Today when I was leaving for work I notice the truck wasn't idling right, it kept trying to die. So put it in drive and it act like it wasn't getting any gas. It wouldn't go with my foot all the way down on the pedal. Now it seems like it's a fuel pump. But how can that be with the code said MAF. Any ideas what could be wrong

Seems like does not get it.:rofl:
Only proper testing will lead you to the problem.

Are you going to the dealer or going to fix it yourself?

If you are going to DIY it.

Post back what code comes back after code clear.
Post back that code no.

If it is same MAF sensor code get the repair flow chart for that code and have at it.

A quick test on the MAF sensor is to unplug it and see if it runs different or better.
If so post back.
But that will set a code.
So you will have to clear codes again and run to see if any codes comes back.
Also make sure connector is plugged in good and no wire damage and make sure all air intake ducks are tight and no leaks.

A quick test on the MAF sensor is to unplug it and see if it runs different or better.
If so post back.
But that will set a code.
So you will have to clear codes again and run to see if any codes comes back.
Also make sure connector is plugged in good and no wire damage and make sure all air intake ducks are tight and no leaks.

Alright, thanks alot guys. During lunch I'll go back and unplug the sensor to see how it acts

Seems like does not get it.:rofl:
Only proper testing will lead you to the problem.

Are you going to the dealer or going to fix it yourself?

If you are going to DIY it.

Post back what code comes back after code clear.
Post back that code no.

If it is same MAF sensor code get the repair flow chart for that code and have at it.

Where could I get the flow chart at

Are you going to DIY it?
Repair flow charts can be found in the factory repair manuals or All Data and Mitchell online DIY repair info subscriptions.

Are you going to DIY it?
Repair flow charts can be found in the factory repair manuals or All Data and Mitchell online DIY repair info subscriptions.

1st thing I'm gonna do is unplug the sensor and see how it drives. But I say I'll end up taking it to the dealer. I just hope it's the mass air flow sensor and nothing huge.

But after I unplug it and drive it. I'll let you all know how it does

It actually done this bout a week ago, kept acting like it was gonna die. But then it just stop so I let it go, but now it's back. So I better take care of it this time lol

Alright, so I upluged the mass air flow sensor and then plug it back up and it seem to do better. Wasn't trying to die no more. But I notice when I did this it would make the truck shift harder. It would only do it when switching from 1st to 2nd, about 10-15mph.

Once I plugged the scanner back up it read 5 codes this time

Po101
Po102
Po113
Po172
Po175

I know that since I unplugged the sensor it added the codes. Should I erase these codes again.
Seems to me like it is the sensor going bad

Alright, so I upluged the mass air flow sensor and then plug it back up and it seem to do better. Wasn't trying to die no more. But I notice when I did this it would make the truck shift harder. It would only do it when switching from 1st to 2nd, about 10-15mph.

Once I plugged the scanner back up it read 5 codes this time

Po101
Po102
Po113
Po172
Po175

I know that since I unplugged the sensor it added the codes. Should I erase these codes again.
Seems to me like it is the sensor going bad

Yes clear codes and drive it.
And let the dealer take care of it if that is the way your going go.
There is No pay check for you or us figuring out the problem for the dealer.
That is what they are paid for and what you pay warranty for.
Let us know how it goes.

If it runs better with MAF sensor unplugged it points to a bad MAF sensor

alright, thanks for all the help.

Just kinda wanted to get an idea of what the problem was.

And would I still have warrenty if I only have 33,000 miles on it?

alright, thanks for all the help.

Just kinda wanted to get an idea of what the problem was.

And would I still have warranty if I only have 33,000 miles on it?

Depends on what warranty you have and what the problem is.
As in post 6 call your dealer and talk to them on the warranty.
Let us know what they say.
First thing.
Proper testing is going to have to be done by you or your dealer.
To find the problem and then your warranty checked to see what it covers.
Let us know how it goes.

You should read what your warranty papers say.

alright, I called this morning and they wont be able to get it in till next monday.

After deleting all the codes Saturday, only 2 came back. they where
PO171 System to lean (bank 1)
PO174 System to lean (bank 2)


Im gonna go through all the papers and see if I can get some info on the Warranty

alright, I called this morning and they wont be able to get it in till next monday.

After deleting all the codes Saturday, only 2 came back. they where
PO171 System to lean (bank 1)
PO174 System to lean (bank 2)


Im gonna go through all the papers and see if I can get some info on the Warranty

the codes you have point to a leaking intake manifold...could be gaskets, vacuum lines , air ducting from MAF to throttle body.

If you had these defects mentioned above , the computer may throw MAF codes. not that the MAF is bad..


It is possible the fuel pressure is low, fuel filter plugged.. best get fuel pressure checked...

if you keep fuel level low and don't use the vehicle often the fuel may be contaminated as well......

the codes you have point to a leaking intake manifold...could be gaskets, vacuum lines , air ducting from MAF to throttle body.

If you had these defects mentioned above , the computer may throw MAF codes. not that the MAF is bad..


It is possible the fuel pressure is low, fuel filter plugged.. best get fuel pressure checked...

if you keep fuel level low and don't use the vehicle often the fuel may be contaminated as well......

No I use the vehical every day, at 1st I though it might of been contaminted fuel, but the next time I got gas it was still doing this.

So the options you listed above would cause the vehical to act like it was dying or make the shift points rough?

No I use the vehical every day, at 1st I though it might of been contaminted fuel, but the next time I got gas it was still doing this.

So the options you listed above would cause the vehical to act like it was dying or make the shift points rough?

when you disconected the MAF it ran poorly and those lean codes came back ..this is because the MAF is part of the air mixture control componets..

the MAF will throw MAF codes normally when BAD ...

your codes as I explained before appear to be from other causes since the lean codes are always there.. poor harsh up shift with a lean condition is to be expected..

It seems you lack the equiptment to test this so as recommended by mt 2500 go to a repair center to get these items mentioned here checked...

alright, so I took my truck back to the dealer, at 1st they though it was an oxygen sensor, so they replaced it, but didn't help. It turn out it was the fuel pump going out. They order me a new one but hasn't came in yet.
I also found out that this was covered under the powertrain warrant, so thats great.

Thanks for all the help guys!

alright, so I took my truck back to the dealer, at 1st they though it was an oxygen sensor, so they replaced it, but didn't help. It turn out it was the fuel pump going out. They order me a new one but hasn't came in yet.
I also found out that this was covered under the powertrain warrant, so thats great.

Thanks for all the help guys!

You are welcome and thanks for posting back how it went.
You are luckie the power-train warranty is taking care of it.
Was wandering how the found bad fuel pump?
Did it quit or just get weak on pressure?

Is it the standard or extended warranty and any deductible on it?

Stratch that. I went to pick my truck up and as soon as I pulled out the check engine light came back on and it was still shifting really hard from 1st to 2nd, and idling poorly when I start it up. I took the truck back as soon as that happen. They've had it since Monday morning and stil can't fix it

But to be honest with you, I think all they done was erase the codes to make me think it was fix, because they couldn't find the bill that said
what they done to it, but then again maybe they did try something. You can't trust dealers

Mt2500 it was just standard warranty

I need to make them give me a rental

But

Ok, so they just called me and told me I got ahold of bad gas. They said they check the fuel with a scanner they got from gm and said my aclohol level in the gas was 12% and was only suppose to be 10% and that was causing it to act like it's missing

Does that sound right to you guys?
Can bad gas make my truck idle bad and not shift right?

They are jacking you around.
Tell them if that is all it is to fix it and show you it is fixed.
But you may have to let them pump it out and put some good gas it it to prove it.

Did they replace the fuel pump and run the full fuel pressure test?
If not get on there case about that.

Yup They said to run all the gas out and then fill it all the way back up


Can I shyper all the gas out with a hose or do they put a wire shell in the tank so nobody can shyper gas out?

Yup They said to run all the gas out and then fill it all the way back up


Can I shyper all the gas out with a hose or do they put a wire shell in the tank so nobody can shyper gas out?

They make them very hard to suck gas out.

disconnect the fill hose at the tank the suck the gas out. at 12% that is not much of a % to couse the problems you have. one thing about ethanol it sucks water then settles in the bottom of the tank. most cars are running on 11 to 15% ethanol.

So, im still having the same problems.

Ran all the gas out, till I had a gallon left. Filled it back up this morning.
While I've had it, I checked all the PVC hoses and they looked fine. no holes or shut together. They said they replaced the fuel pump on it, so thats out. I test the fuel pressure and it was fine. MAF is fine.

Whats some other things it could be, I'd like to look myself and when I find it, take the problem to them. Cause I almost gurantee that the gas is not causing the problems I have.

I've also notice that my exhaust is producing more smoke out the pipes then usually.
So besides the MAF,Fuel pump,PVC hose and valves, what else could be causing the problem.

Could spark plugs cause this.

you best believe if not running out all the gas works then imma flip shit. this is ridiculous!

Yup They said to run all the gas out and then fill it all the way back up


Can I shyper all the gas out with a hose or do they put a wire shell in the tank so nobody can shyper gas out?

I was thinking earlier in this issue you have about bad fuel. or the fuel pump. so exactly what fuel station company did you purchase your fuel ?

the fuel pressure needs to be measured and post here what you found . the dealership is full of bull shit , when they say there is 12 % alcohol in fuel . some times you need to go top another repair shop to get this fuel pressure data . then with all this written down by the testing repair center go back to dealership with a witness..need a witness this way they are less apt to screw you / lie to you . then if possible go to another dealership but do not mention what happened at this bad dealership.

when this is repaired it should be reported to the consumer affairs office in your state goverment , what actually occured .

Right on tract.
As J cat said.
That dealer does not know what they are doing or just jacking you around.

Get that full pressure tested by some one else.
Hook up a fuel pressure gauge and drive it hooked up.
Always check fuel pressure threw all ranges cold and hot after driving 1/2 hr or more.
Make sure it is up to specs at all times.
Also check full fuel pump pressure.
Some times if a pump is just weak enough to hold spec they can be weak in fuel volume.
A good pump Full pressure should be 95 lbs or more to be able to hold good fuel volume at spec pressure.

If so move onto the maf sensor code if it is still there.
Dirty sensor or bad wiring or leaking air intake to TB or intake gasket leak air or bad sensor.

hey guys, figure I would get back on here and let you know what the problem was.

it was the Mass Air Flow Sensor. Which I though it was at first lol..

and it was covered under warranty.

Thanks for all the help

hey guys, figure I would get back on here and let you know what the problem was.

it was the Mass Air Flow Sensor. Which I though it was at first lol..

and it was covered under warranty.

Thanks for all the help

happy to hear the DEALERSHIP has corrected this defect ..

Sorry about how they put you through all this , as this is not hard to troubleshoot with the proper equiPment and half a BRAIN !

happy to hear the DEALERSHIP has corrected this defect ..

Sorry about how they put you through all this , as this is not hard to troubleshoot with the proper equiPment and half a BRAIN !

yea really, but thanks for all the help Jcat and MT-2500. Now I can get the bumper that I bought painted finally lol..