P0104
Mass or Volume Air Flow Circuit Intermittent
Powertrain Fuel and Air Metering Air Flow Measurement 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

Your engine's air flow sensor is sending inconsistent signals to the computer, like a flickering light switch. The ECU can't reliably measure how much air is entering the engine, causing it to struggle with fuel timing and delivery.

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Symptoms You May Notice
3 known symptoms for this code
Check Engine Light illuminated
Rough idle or stalling
Hesitation during acceleration
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Embedded Systems Insight
What the ECU/ECM is actually computing

The Mass Air Flow (MAF) sensor measures incoming air density and volume by detecting heat loss across a hot wire. The ECM expects a steady, predictable signal voltage that correlates to engine load. Intermittent faults occur when the sensor signal drops out momentarily or fluctuates erratically, exceeding acceptable variance thresholds.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
MAF Sensor Voltage 0.7–3.0V at idle, smooth ramp under load Erratic jumps, dropouts, or signal noise >0.5V deviation
MAF Flow Rate 3–7 g/s at idle, linear increase with RPM Intermittent spikes/valleys or readings inconsistent with RPM
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
MAF sensor connector
Inspect and reseat the connector; clean contacts with electronic contact cleaner to eliminate intermittent electrical connection.
2
Air intake hose
Check for cracks, splits, or loose clamps that allow unmetered air to bypass the sensor and cause false readings.
3
MAF sensor element
Clean the sensor's hot wire with MAF sensor cleaner; do not touch the wire directly as it is delicate and contamination causes intermittent faults.