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CarQuestionGuy, Technician
Category: Car
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Experience:  ASE Master Auto Technician for 5 years, ASE Refrigerant Handler, ASA, iATN
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525: getting p0102, replace vacums lines and mass sensor,

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Getting p0102, engine idles ok, no test drive.

Replace vacuums lines and mass sensor, put the scanner on it and won't detect the mass air flow going thru the sensor, reading 0

Clear code , check engine gone after restarting engine code comes right away. I will say electrical problem, I inspect the wires did not find any problem.


Did you inspect the vacuum lines with a flashlight?
The only reason I ask is because these are a high failure rate item. I would even remove the main air hose from the air box to the throttle body and inspect it very carefully to be sure there there isn't anything wrong with it.

Let me know and we can go from there.
Customer: replied 4 years ago.
Intake was out and all the parts required and recommended by the dealer where replaced by me with oem parts, I pull and check hoses connected to the throttle did not find anything.
What is strange as soon as clear code and restart again the engine the code p0102 is popping on and engine idles normal. There is no difference if mass sensor is connected or discomected and when I read it with the scanner reads 0 no air movement thru the sensor
Do you have a cold air intake installed? Any other mods?
you have ruled out a vacuum leak and you have ruled out the MAF being the problem. The next thing to start looking at is the wiring. There are really only two things left that can cause this problem, either the wiring or the computer. It is extremely unlikely that the computer is bad so I would think that the wiring probably is causing this problem.

Basically you need to check the wiring from the MAF to the computer. There are no known common problems with this wiring so you pretty much have to check it all. Be sure to check around where any recent work has been done. Check the connectors very carefully too. I would unplug them and plug them back in to be sure they are seated.

Let me know what you find and we can go from there.
Customer: replied 4 years ago.
There is no cold intake on this car , oem air cleaner box .I will check every single conennector that is being touch
when I did the service on it, this is I believe could be the problem?
I will keep you inform Tomorrow
Thank you for now!
OK. Let me know what you find.
Any luck?
Customer: replied 4 years ago.


I can't get this problem solved, I look all the hoses and unplug all the connectors and plug it back, and nothing was disconnected.
I check all the wires and test the mass air sensor wire to the big chunks of the wires going inside car, have continuity and check fuses again in the passenger glove box but I can't find the problem.

I did not have this code before, it came after hoses replacement.

I don’t think computer is bad, when working on the car battery was disconnected.




Wait, what hose replacement?
Customer: replied 4 years ago.

this is what I did:

crankcase vent valve hoses

valve cover gasket

vanos hoses

upper throttle hoses and lower hoses


If it didn't have the codes before this but it has them now I would be really checking those hoses, especially the connections. Unless this is just coincidence there has to be a problem there.

You might try spraying some starting fluid around any of the vacuum hoses you replaced to see if the rpms pick up. This would indicate a leaking hose.
Customer: replied 4 years ago.

I spray fluid no difference!

When I hock up the snap on scanner won't read at all (0) the mass sensor, this is like it won't be there, if i unplug it or plug it there is no difference. Sounds like a electrical problem, if I clear the code when I restart the car comes on right a way.

It makes me nervous since this problem didn't happen before replacing the hoses. Since you have checked it I guess we can test other things...I just think there is something there that we are missing.

Anyway the next thing we need to check is if the MAF is getting voltage from the computer and if it is sending the correct voltage back to it. It will take a bit for me to look up the wiring diagram. I'll post back as soon as I do.
First you need to check for battery voltage at the Airmass Meter on the white/red wire.
Check that and let me know what the voltage is. Also, check the battery to see what the voltage is across the two terminals.

Let me know these voltages then we will go from there.
Customer: replied 4 years ago.

Ok engine off I have 11.73 v on the battery w engine on I have 13.89v

White and red wires mass sesor wires w engine on 13.68v

OK. Then check the ohms on the black wire. We need to see if it is getting a good ground.

After that check the voltage on the yellow wire with the engine on.

BTW. Your battery needs to be tested as well. 11.73 volts is not enough. I surprised your car even starts. You probably need a new battery.

Let me know those voltages.
Customer: replied 4 years ago.

Right now battery has over 12v I had doors open, but car cranks right up.

Forget to mention on the mass sensor wire I have

red with white stripe




I check black wire with yellow wire and has 4.6 ohms if this is what i need to do ? with engine on.

or how do I check the ohms ? with just one wire connected on the tester won't read nothing , do I use ground with the other wire from the tester?

To check ohms on the black wire you just need to probe the black wire with one of the voltmeter leads then put the other lead to ground. Be sure to have the meter set to ohms.

Let me know the ohms reading

Then check the voltage on the yellow wire with the engine running and let me know what the voltage reading is.

BTW, 12 volts is still not enough. It should have a MIN. of 12.6 volts.

You need to get this battery situation fixed asap. None of this testing will be accurate without a good battery.
Customer: replied 4 years ago.

w engine off

black wire mass sensor and ground the other leads set up the voltmeter to ohms 0.46 and going down to 0.00

w engine running black wire and ground reads

0.68 fluctuating up and down

w engine running yellow and ground reads

3.86 fluctuating up and down


battery has a voltage of 12.26 cranks the car up w no problem

I can charge the battery if this will make a diffrence, I don't have battery here to replace it , I can put a jump box to it?

You now need to go to pin #1 on the cars computer (Rear right side of engine compartment) and check the voltage on that wire. It is still the yellow wire.

Then you need to check the black wire at the computer for ground. Hook one lead into the black wire and the other to a good ground and check the ohms.

I would put a jump box on the battery to charge it up.

Let me know what you find.

Customer: replied 4 years ago.

i have two computers in the rear right under the hood

first one blue looking 3 connectors with wires

second computer black looking with 4 connectors

which computer and which connector ?

thank you

It should be the one with 3 connectors. You should be able to see the numbers printed on the connectors too. Just be sure these numbers match with the wire colors.

You should have a connector with pin#1 that is a yellow wire.
On that same connector you should have a pin#17 that is black. This is the MAF ground.
Customer: replied 4 years ago.

it is the computer with 4 connectors I track the wires they have continuity yellow wire and black wire.

pin#1 yellow wire I check w engine running and not running for voltage there is nothing , I check pin 1 with ground and also check between black and yellow is showing 0


pin#17 black wire w engine running has 2.48 ohms or w engine off has 0.07 fluctuating

Hmm...the wiring diagram I'm looking at it showing 3 connectors. I look into this more.

Let's make sure we have everything right:

1) When you check the yellow wire at the sensor it is showing 3.86 volts. When you check the yellow wire at the computer connector it is showing 0 volts. Is this correct?

2) The black wire has a resistance (ohms) reading of 2.48Ohms with the engine running?

Assuming we understand each other there seems to be a problem with the yellow wire. It should read the exact same at the sensor as at the computer. This wire needs to be traced to find out why we are losing voltage.

The ground reading is strange too. It should be grounded. It should read 0 ohms (this simply means there is no resistance from the wire to ground, meaning that there is a good connection.)

Customer: replied 4 years ago.

if you look the post you where asking me to test white and red for voltage which what i did was testing yellow and red, there is no white;

you did not mention to test voltage on the black with yellow wire, only the ohms

However I check at the mass connector yellow and black and there is nothing ( 0 )voltage as well 0 at the computer connector.


But there is voltage on red with yellow 13.86v w engine running


pin#17 black wire w engine running has .78 ohms

on this one the voltmeter was set up higher sorry my fault on this.


OK. My bad. It is a RED wire with a White stripe. I misread the diagram. This wire should have battery voltage at the sensor.
What is the voltage at the Red/White wire at the sensor with the engine running?

Then there should be a solid Yellow wire at the sensor.
What is the voltage on this Yellow wire with the engine running?

There should also be a solid black wire at the sensor. This is the wire that we need to check resistance to ground on.
What is the ohms reading on the black wire when one lead is probing the black wire and the other lead is toughing a good ground?

Does this make more sense?
Have you been able to do this yet?
Customer: replied 4 years ago.
Sorry was not able to get to the car today
Red/white 13.68v w engine running
Yellow 0 no voltage w engine running
Black 1.09 ohms
It looks like there is normal voltage on the Red/white.
The yellow doesn't have any and it should.
The black should not have that much resistance.

Let's try one thing before we move on. Let's run another ground wire and hook it to the black wire to see if it will make the MAF work. After hooking the black to ground then re-check the yellow.

At some point we will also need to test the frequency on the yellow wire. This is the best test to see the output of the MAF. The best way to do this test is with an oscilloscope.

If you hook the black to ground and the MAF still doesn't work, then The only thing left is to return the MAF for another.
Customer: replied 4 years ago.
I pick up another mass sensor this morning and guest what I installed and works fine - no more codes
I will get you paid for your time and help!
Thank you!
Awesome! I'm glad it's fixed. I HATE it when I get bad parts it just makes everything so much harder to diagnose.

Let me know if you need anything else in the future.
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