Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Mass Air Flow And Intake Air Temperature Sensor
Overview
The component is a combined sensor and contains two sensors in the same component:
- Mass air flow sensor
- Intake air temperature sensor
Mass air flow sensor
The mass air flow sensor gauges how much air mass is sucked into the engine and continuously transmits signals to the Engine Control Module (ECM) about the mass of the intake air. The information is used by several functions and calculations in the control module, both for diagnostics and engine control.
The mass air flow sensor is a hot wire type. Unlike other hot wire types, this mass air flow sensor uses a hot wire which has a ceramic casing. This eliminates the need for a clean burn function.
The mass air flow sensor is supplied with voltage (12V) by the system relay and is grounded in the Engine Control Module (ECM). The signal from the mass air flow sensor is a frequency modulated (FM) signal (5V) where the frequency varies with air mass.
For information about electrical connection, see wiring diagram. For sensor characteristics and normal values, see signal specification and component specification.
The mass air flow sensor can be diagnosed by the Engine Control Module (ECM) and the sensor signal can be read off.
Intake air temperature sensor
The temperature sensor measures the temperature of the intake air. The information is used by several functions and calculations in the control module, both for diagnostics and engine control.
The sensor, which is an NTC resistor, is grounded in the control module and supplied with power (signal) from the control module.
The signal from the sensor is analogue and varies with temperature.
For information about electrical connection, see wiring diagram. For sensor characteristics and normal values, see signal specification and component specification.
The temperature sensor can be diagnosed by the Engine Control Module (ECM) and the sensor signal can be read off.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.