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Mike V.
Mike V., Hyundai Technician
Category: Hyundai
Satisfied Customers: 25478
Experience:  I have over 25 yrs. experience on all makes and models. Factory trained for Subaru and Nissan.
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Mike, I have a 2004 Hyundai Sonata with a 2.7 engine and

Customer Question

Hi Mike, I have a 2004 Hyundai Sonata with a 2.7 engine and im getting code p0102 maf. I replaced The mass air sensor and did not solve the problem. The car seems to hesitate every so often. My next step is to check The wiring. I need your assistance"
Submitted: 1 year ago.
Category: Hyundai
Expert:  Mike V. replied 1 year ago.
HI there,Do you have a volt meter and is this code still showing even with the new sensor?
Customer: replied 1 year ago.
yes and yes
Expert:  Mike V. replied 1 year ago.
Ok, first thing we have to do is make sure it's getting power. Do this on pin 3, key on, it should have battery voltage. Pin 1 should show continuity to ground. Both of these are on the wiring harness side, not the sensor side.Then the final pin/wire, #2 is our signal wire. With the sensor plugged in and the engine running, voltages will have to be checked.Idle: .6-1.0 volts2000 rpms: 1.3-1.5 volts3000 rpms 1.7-1.9 volts.I am sending along a diagram of the harness side connector with pin #'s to help.Check it and let me know.Thanks.
Customer: replied 1 year ago.
just making sure is pin 1 the pink wire?
Expert:  Mike V. replied 1 year ago.
The service manual doesn't give me the color of the wires, The tab for the release should be on top when you are looking at the connector from the end that plugs in.
Expert:  Mike V. replied 1 year ago.
Found it in the wiring diagram.Pink is #3, yellow for #2 and looks like black/yellow stripe is the #1 pin
Customer: replied 1 year ago.
we have continuity to ground, battery voltage on pin 3 and the signal seems to be with in those specs. when i snap the throttle it jumps up to 3. volts or more.
Expert:  Mike V. replied 1 year ago.
Ok, the next step is a fun one. You are going to need to check the signal wire at the computer unless you have a scan tool this will have to be done manually by locating the wire and measuring it like you did out at the sensor. Do you happen to have a code reader that can see the live data from the maf sensor? Some code readers can do this as well.
Customer: replied 1 year ago.
yes, I have a snap on solus
Expert:  Mike V. replied 1 year ago.
Ah, well that should help :)I haven't used one myself so I hope you can see both the voltage and I am also sending the actual kg/h you should see at the various RPMS.Also, if you can set it up, we could watch the TPS and MAF to make sure they kind of mimic each other on a graph.Lets try this step first. I prefer the measurement of the amount of air it's sending over the voltage testing. Its usually more reliable in my opinion.
Customer: replied 1 year ago.
MY scanner is showing MAF... G/S. Is that the same as kg/h?
Customer: replied 1 year ago.
i can only seem to get voltage on the graph for the maf
Expert:  Mike V. replied 1 year ago.
No, I don't believe it is. That would be grams/second. Guess we can get that reading and see if google can do the math for us.Volts is ok for the graph, same with the tps, we are just looking to make sure the maf reacts quickly to the voltage change on the tps. In other words, when you open the throttle the maf should show a higher voltage.
Customer: replied 1 year ago.
The maf does show higher voltage than the tps. The tps voltage shows under .6 volts when sweeping throttle with engine running. I forgot to mention every once in awhile when driving the car the engine will cut out briefly, like bog but return to normal quickly.
Expert:  Mike V. replied 1 year ago.
Sure seems like a maf symptom to me, I wonder if there is a problem at the connection, or inside the maf that's not consistent. Possibly try a wiggle test on the harness with the car running. If there is a problem at the connection it should show up. Otherwise I would try another maf sensor. I mean it is showing the no power to it code when it's failing. might be the only answer.
Customer: replied 1 year ago.
I do not think the maf is the problem, this is the 2nd one I tried. lets go back to testing the wires at the computer, Does this have to be done manually or will the scanner pick it up?
Expert:  Mike V. replied 1 year ago.
If your scanner can see the voltage from the maf sensor, then it should read the same as what you found up at the sensor. If the scanner doesn't show the voltage you have to go to the computer and back probe the wiring harness right there and use the meter.
Customer: replied 1 year ago.
What are some common cause for p0102 other than the maf? I am stumped and cant seem to solve this issue!
Expert:  Mike V. replied 1 year ago.
With the code the options are limited. The code is basically telling us there is a problem with the wiring, the sensor or the computer.These cars are known to have problem with the connectors losing contact, but what I think here is the sensor wire gets hot and loses or stops sending the signal. You could verify it if you can drive the car with the scanner on it. When you feel it running rough, or some type of issue with the driving or the way the engine is running and see if you can pick up the change in the maf. You can do this with the voltage or the g/s reading you can see. The maf should remain basically steady when you are at cruising speed.If you are using aftermarket maf sensors, I am not sure I would trust them. I know my personal experience with my own vehicles hasn't been great with aftermarket maf sensors.This is why I was thinking a wiggle test while watching the scan tool might show up something.The only other thing I could see having affect would be a vacuum leak or a dirty air filter.
Customer: replied 1 year ago.
what should THE INTAKE AIR TEMP READING BE?
Expert:  Mike V. replied 1 year ago.
It is usually within 10 degrees of the ambient air temp. Most of the time it is a bit warmer because the engine compartment should be warmer when the engine is running.
Customer: replied 1 year ago.
do you know what the crankshaft sensor reading should be? it shows no reading on scanner but the car runs.
Expert:  Mike V. replied 1 year ago.
You can only graph the crank sensor.
Customer: replied 1 year ago.
ok, I tried a new oem maf and code p0102 low circuit is still popping up!
Customer: replied 1 year ago.
I want to back probe the 3 wires at the ecm, can you walk me through the process? also where is the ecm located? thanks
Expert:  Mike V. replied 1 year ago.
The ecm is mounted below the heater box by the gas pedal. I am sending a diagram of it's location. You will see I highlighted some numbers. Pay attention, they are the connector numbers. I will find the signal wire you have to back probe and send it. It will be labeled with the connector number first, then the wire #. This will have a diagram as well like the one I sent to you for the maf sensor.
Expert:  Mike V. replied 1 year ago.
You want connector C94-3 then pin 1 which is a yellow wire. I usually use a pin and push it into the back of the connector at the wire. Then attach the meter there. A quilters pin works the best as they are T in shape and have something you can grab onto with the meter.
Customer: replied 1 year ago.
There is signal and its with in range. I am going to drive it around with to see if there are any abnormal readings.
Expert:  Mike V. replied 1 year ago.
Seems like the next step, either there is something going on with the wiring or the computer. Can't see it being anything else. The key here is the reading should be the same at both ends. That would eliminate the wires as the problem
Customer: replied 1 year ago.
my reading on intake air temp is 3.0 v @ 180 degrees and should be much lower when intake temp rises, Does this reading seem normal to you?
Expert:  Mike V. replied 1 year ago.
They don't provide me with a voltage reading.Only a resistance reading. Sending the spec.
Customer: replied 1 year ago.
Can you give me signal and ground location at ecm?
Expert:  Mike V. replied 1 year ago.
Yes, but you check the resistance on the 2 pins on the sensor with it unplugged.Same connector as before, pins #22 and #23
Customer: replied 1 year ago.
I bought a new sensor and the voltage is still too high so I am thinking it is a wiring or computer issue.
Expert:  Mike V. replied 1 year ago.
are you talking about the IAT? I don't see a voltage spec on the IAT so I am not sure about it.
Customer: replied 1 year ago.
yes, I want to check continuity and resistance on the signal wire and ground at ecm.
I need to know what connector and what #
Expert:  Mike V. replied 1 year ago.
Yeah, it' what I said,Same connector as before C94-3, pins #22 and #23But the resistance spec I gave to you is for the sensor itself.
Customer: replied 1 year ago.
oh...ok
Expert:  Mike V. replied 1 year ago.
Not to suggest you can't check the continuity on the wiring to the computer but the actual spec I gave was out at the sensor itself unplugged.