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.
Circuit/System Description
The mass air flow (MAF) sensor is integrated with the intake air temperature (IAT) sensor. The MAF sensor is an air flow meter that measures the amount of air entering the engine. The engine control module (ECM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. The MAF/IAT sensor has the following circuits:
- Ignition 1 voltage
- MAF sensor ground
- MAF sensor signal
- IAT sensor signal
- IAT low reference
The purpose of this diagnostic is to analyze the performance of the MAF sensor by comparing the measured airflow to the following 2 distinct models:
- The first model is separated into two parts. The first part is based on basic engine parameters and uses engine speed, and throttle angle as inputs. The second part is derived from long term fuel trim, at cruising speed and the ECM is looking for an adaptation value to be within a calibrated range.
- The second model uses the manifold absolute pressure (MAP) sensor for input, and the ECM is looking for an adaptation value to be within a calibrated range.
NO RELATED
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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.