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Engine Sensor Voltage: Technical Interpretation

This visual guide from Auto Avance shows the typical voltage ranges provided by five essential engine sensors when measured with a multimeter. All of these sensors operate with direct current (DC) voltage, and their signal is measured relative to ground.

Each has a specific behavior:

ECT sensor: Its voltage decreases as the engine warms up. A high value indicates a cold engine, and a low value indicates it has reached operating temperature.

Zirconium oxygen sensor: Its voltage constantly fluctuates between 0.1 and 0.9 V when the engine is in closed loop mode. If the value remains fixed, it indicates a fault or an unbalanced mixture.

TPS sensor: When accelerating, its voltage should rise progressively. At idle, it reads between 0.5–0.9 V, and at full throttle, it reaches approximately 4.5 V.

MAF and MAP sensor: The voltage varies with engine load. At idle, expect between 1 and 2.5 V depending on the design. Fixed or out-of-range values ​​may indicate a dirty or damaged sensor.

👉 Remember: If the voltage remains completely fixed or outside these ranges when measuring any of these sensors, it's a clear sign that something is wrong.