I want to point out that many mass air flow sensor failures are actually the result of an external problem. When installing or replacing a unit, make sure to determine why the original unit failed, so the same failure does not occur with the replacement unit. Shorts in the wiring, failed connections, contaminated air flow or an improperly tuned engine, are all culprits that could lead to a replacement unit failure. However, the following tips should help ensure your MAF sensor installation is a success.
First, check for trouble codes. The vehicle may have problems that are preventing the sensor from operating properly. Repair or correct, as required. Next, inspect the wiring and connectors and repair, as necessary. Then, verify the reference voltage and grounds. Typically, the ECM supplies a regulated reference voltage to the sensor. If the reference voltage isn't present or incorrect, check the ECM for proper operation. In addition to performing ground continuity test, you should also perform voltage drop test on all grounds. Be sure to eliminate any vacuum leaks downstream on the MAF sensor. If not corrected, this would introduce unneeded air into the system resulting in a drive-ability issue and most likely a check engine light. Inspect the air inlet duct and connections and check for any loose clamps, duct cracks, or other damage. Then, check all air ways for obstruction and replace the air filter with the OE approved filter. Keep in mind that some high performance filters may not actually meet OE standards.
You want to protect the replacement unit from static electricity discharge and disconnect the battery ground cable before unplugging the MAF unit. Don't forget to provide alternative power to the vehicle to avoid loss of adaptive strategies and settings in those modules. This can be done by using a memory saver tool, like this one. Next, inspect the weather seal on the pigtail connector. If it is in bad shape, replace the seal or pigtail connector, as needed. Sometimes the seal gets stuck in the original mass air flow unit when you remove the pigtail connector. So, if you can't find it on the connector, check the original unit. The last step is to check for proper operation using a diagnostic scanner if you have one available. Verify the sensor data and check for any diagnostic trouble codes. As always, be sure to follow the vehicle's service manual for specific diagnostics and complete installation instructions.