The Mass Air Flow Sensor (MAFS) is located between the air cleaner assembly and the throttle body. The MAFS uses a hot film type sensing element to measure the mass of intake air entering the engine. This hot film type air flow sensor consists of a hot film sensor, housing and metering ducts. Mass air flow rate is measured by detection of heat transfer from a hot film probe. The change in air flow rate causes change in the amount of heat being transferred from the hot film probe surface to the air. A large amount of intake air represents acceleration or high load conditions while a small amount of intake air represents deceleration or idle. The mass of intake air should increase at acceleration and be stable during constant engine speed. The PCM uses this information to determine the injection duration and ignition timing for the desired air/fuel ratio.
The difference between values coming from the MAF Sensor and those are calculated is analyzed. This difference, or error, is then compared to high and low limit calibration values, which are functions of engine speed. PCM compares MAFS output to calculated flow rate value while enable condition is met.
If the actual air flow is higher than Maximum threshold, or lower than Minimum threshold for more than 75 seconds failure for every 125 seconds test. PCM determines that a fault exists and a DTC is stored. MIL(Malfunction Indicatin Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Compares the difference between MAF Sensor output and calculated flow rate value to a calibration value | ● Poor connection ● Open or short in harness ● Clogged air cleaner ● MAFS ● PCM |
Enable Conditions | ● Barometric Pressure enable conditions criteria met ● Engine Coolant Temperature ≥ 60°C ● 600rpm < Engine Speed < 3000rpm ● Air Conditioning Clutch not transitioning ● Torque Control is not Active ● Traction Control is not Active ● Brake switch is not active ● Current Transmission Torque Converter Clutch State same as previous ● Power Steering is not Cramped ● Engine Speed difference ≤ 300rpm ● TPS value difference ≤ 5% ● MAP value difference ≤ 7 kPa ● Idle Airflow difference ≤ 10% ● Cam phasing control changes ≤ 10% ● MAP/TPS Rationality High Power Condition Fail Criteria Not Met ● MAP/TPS Rationality Low Power Condition Fail Criteria Not Met ● MAP/TPS Rationality Decel. Condition Fail Criteria Not Met ● BARO Update Enable Criteria Met ● Enable Timer ≥ 1.5s | |
Threshold value | ● Comparision result value is out of calibration value | |
Diagnosis Time | ● Continuous (More than 75 seconds failure for every 125 seconds test) | |
MIL On Condition | ● 2 Driving Cycles |
Air Flow (kg/h) | Frequency (Hz) | Air Flow (kg/h) | Frequency (Hz) | Air Flow (kg/h) | Frequency (Hz) |
0 kg/h | 720 ~ 880Hz | 43.2 kg/h | 3,975Hz | 270.0 kg/h | 7,219Hz |
12.6 kg/h | 2,595Hz | 57.6 kg/h | 4,361Hz | 360.0 kg/h | 7,945Hz |
18.0 kg/h | 2,930Hz | 72.0 kg/h | 4,683Hz | 486.0 kg/h | 8,736Hz |
23.4 kg/h | 3,208Hz | 108.0 kg/h | 5,362Hz | 666.0 kg/h | 9,660Hz |
32.4 kg/h | 3,609Hz | 198.0 kg/h | 6,527Hz | 900.0 kg/h | 10,613Hz |
