DTC P219A: Air/Fuel Ratio Variation of Cylinders: General Description

Fig 1: Air/Fuel Ratio Sensor Operation Diagram

The powertrain control module (PCM) measures the air/fuel ratio by the signal from the air/fuel ratio (A/F) sensor (sensor 1). If the air/fuel ratio varies between cylinders, the signal from the A/F sensor (sensor 1) fluctuates while all cylinders complete the combustion cycle (two engine revolutions as one cycle). The PCM extracts the air/fuel ratio fluctuation of one cycle from the A/F sensor (sensor 1) signal, and integrates the extracted value at a specified duration. When the integrated value exceeds a specified value, the PCM detects a malfunction and stores a DTC.