The 2019 Nissan Altima's P0104 code indicates the ECU detected intermittent or erratic signals from the MAF sensor. Unlike constant high or low codes, intermittent codes suggest a connection issue that comes and goes—often the most frustrating type to diagnose.
What P0104 Means
P0104 specifically indicates the MAF signal is dropping out, spiking, or otherwise behaving erratically. The sensor may work normally most of the time but periodically send incorrect data. This intermittent nature often points to loose connections, damaged wiring, or a sensor that's partially failing.
Altima Engine and MAF Location
The 2019 Altima uses either a 2.5L four-cylinder or a 2.0L turbocharged Variable Compression engine. Both rely on MAF sensors in the intake tract. The sensor location subjects it to engine vibration and temperature cycling, which can aggravate intermittent connection issues over time.
Common Causes of Intermittent MAF Signals
Loose or corroded connectors are the primary cause of intermittent issues. The connector may seem secure but have internal corrosion or worn terminals that lose contact under vibration. Disconnect and inspect both the connector and sensor terminals.
Wiring damage that causes intermittent contact is common. A wire may be partially broken internally but still make contact most of the time. Vibration or temperature changes cause it to disconnect momentarily. Carefully inspect and flex wiring while monitoring live data.
A sensor with failing internal components may work intermittently. Heat cycling over years causes solder joints or connections inside the sensor to become unreliable.
Diagnostic Strategy
The key to diagnosing intermittent issues is catching them in the act. Connect a scan tool and monitor MAF data while gently wiggling the connector and wiring. Drive the vehicle while monitoring to see if readings spike or drop out. Check for correlation between symptoms (stumble, hesitation) and MAF data anomalies.