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Carhelp4u
Carhelp4u, ASE CERTIFIED TECH
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99 Chevy Tahoe w/5.7 engine-P0102-Mass air flow sensor circuit-low

Customer Question

99 Chevy Tahoe w/5.7 engine-P0102-Mass air flow sensor circuit-low input. What does that mean and how do you fix it? Please be specific and detailed in responding.
Submitted: 5 years ago.
Category: Chevy
Expert:  Carhelp4u replied 5 years ago.
There are a few places that a problem like this could happen at. Here is a description of what is happening to cause for this problem.

The mass air flow (MAF) sensor is an air flow meter. The control module supplies the MAF sensor a signal circuit. An ignition positive voltage circuit and a ground circuit are supplied to the MAF sensor by independent circuits. The MAF sensor heats a wire element, or grid, within the MAF sensor in order to maintain a calculated temperature. As inlet air flows across and cools the grid, the MAF sensor increases current flow to the grid in order to maintain the constant grid temperature. The MAF sensor converts the grid current flow into a frequency signal. The control module converts the MAF signal frequency into a grams per second value. During low air flow rates, such as at engine idle, the MAF sensor produces a low frequency signal. During high air flow rates, such as at wide open throttle-road load, the MAF sensor increases the frequency signal. The control module monitors the MAF sensor signal frequency in order to calculate the flow and mass of the air entering the engine.

This DTC is designed to detect an unusually low MAF sensor signal frequency. If a MAF sensor frequency is detected by the VCM below the possible range of a normally operating MAF sensor, this DTC will be set.

 

As far as testing is concerned we really need to verify that there is a 12 volts at the meter on terminal C (with key in the on position) and that terminal B is a good ground. We also need to check the signal from the mass air flow sensor to the vehicle control module. This would be terminal #28 with the yellow wire. With the key on you should see 5 volts at this point. Another thing to look at would be the quality of the actual sensor. If you look through the bore and note the diodes are dirty, you may want to try a little CRC MASS AIR FLOW CLEANER to see if this cures this problem. These would all be prelimary tests to determine if the wiring is all in order for starters. Feel free to contact me with any questions! Here is a schematic of this system.

graphic

Customer: replied 5 years ago.
The last time this happened was in August when I was on a road trip. I used the cleaner to spray everything and it worked. Here again I'm on the road and it happens again. What's that trying to tell me??
Expert:  Carhelp4u replied 5 years ago.
Are you using a K&N air filter? Have you checked the air cleaner assembly to verify that there are no leaks?
Customer: replied 5 years ago.
Am using stock air filter and assume everything is tight.
Expert:  Carhelp4u replied 5 years ago.
Ok well I have seen this cause from over oiling a k&n air filter, and also if you have a crack or missealed air filter box. This can allow debris past the air filter and to the air meter. You may also want to look for any traces of oil residue. If oil residue is noted, I would recommend replacing the pcv valve for starters.
Carhelp4u, ASE CERTIFIED TECH
Category: Chevy
Satisfied Customers: 5203
Experience: ASE CERTIFICATION
Carhelp4u and 15 other Chevy Specialists are ready to help you
Customer: replied 5 years ago.
Just checked all clamps and they are tight. Will spray sensor tomorrow and clear code to see if it works.
Expert:  Carhelp4u replied 5 years ago.
Ok let me know how you make out. I will assist you however I can.

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