I was having some sporadic CE light activity upon start where sometimes, the light would come on and the engine would run rough for a while. After some time, the engine would settle down and the light would turn off. I managed to get code 0102. I think I saw that mentioned before, but I was unable to locate it via search.

 

Diagnostic Trouble Code 0102 points to a problem with the Mass Air Flow Sensor. The MAFS is placed in the stream of intake air. It measures the intake flow rate by measuring a part of the entire intake flow. It consists of a thin film that is supplied with electric current from the Engine Control Module. The temperature of the hot film is controlled by the ECM a certain amount. The heat generated by the hot wire is reduced as the intake air flows around it. The more air, the greater the heat loss. Therefore, the ECM must supply more electric current to the hot film as air flow increases. This maintains the temperature of the hot film. The ECM detects the air flow by means of this current change.

This malfunction is detected when an out-of-range voltage is sent to the ECM. That voltage might be too high or too low.

a) An excessively high voltage from the MAFS is sent when the engine is not running.
b) An excessively high voltage from the MAFS is sent under light load driving conditions.

Possible causes include...
- Harness or connectors (the sensor circuit is open or shorted.)
- Faulty MAFS

c) An excessively low voltage from the MAFS is sent when the engine is not running.
d) An excessively low voltage from the MAFS is sent under heavy load driving conditions.

Possible causes include...
- Harness or connectors (the sensor circuit is open or shorted.)
- Intake air leaks
- Faulty MAFS

With DTC 0102 the ECM is supposed to switch into Fail Safe mode and limit engine speed to 2400 rpm.

 

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