DTC P2A03: Front Air/Fuel Ratio (A/F) Sensor (Bank 2, Sensor 1) Circuit Range/Performance Problem: General Description

The front air/fuel ratio (A/F) sensor (bank 2, sensor 1) has a linear signal output in relation to the oxygen concentration. The engine control module (ECM)/powertrain control module (PCM) computes the air/fuel ratio from the front A/F sensor output voltage and uses the fuel feedback control to improve exhaust emissions. The ECM/PCM monitors the front A/F sensor output voltage during deceleration with the throttle fully closed, if the output voltage deviates greatly from normal oxygen concentration levels, and it detects a malfunction and stores a DTC.

* Output to the scan tool exhibits a relationship between the front A/F sensor output and oxygen concentration, which is opposite to the characteristic shown in the graph. That is, a deviation toward the rich side increases the output voltage and one toward the lean side decreases the output voltage as the stoichiometric ratio is 0.