The Wiggle Test
The technician received a code for a faulty (MAF) Mass Air Flow sensor. These plugs are often removed when replacing a stubborn air filter. Leaving the connector loose will wreak havoc on the engine’s operation. By visually inspecting this connection and component, the technician may find the code was caused by a loose connector.
While monitoring the scanner and wiggling the plug or connector, the technician is able to tell if the connector is at fault or if the MAF sensor is faulty. It's important to rule out circuit problems like the connector or poor wiring before replacing expensive components.
Notice the technician is wiggling the wires as well as the connector. This is because wires can break inside the insulation, resulting in resistance and open circuits. This can sometimes be felt in the heat coming from that spot in the frayed wiring. Perform a wiggle test on lighting circuits and any circuit where a loose connector or a broken wire is suspected. Plugs become spaded and must be replaced or repaired to restore the circuit.