Symptoms

- Engine Light ON (or Service Engine Soon Warning Light)

Possible Causes

For Models 2005 and up: - Air Fuel Ratio Sensor 1 Bank 2 circuit is open or shorted - Air Fuel Ratio Sensor 1 Bank 2 circuit electrical connection - Faulty Air Fuel Ratio Sensor 1 Bank 2 For Models before 2005: - Heated Oxygen Sensor 1 Bank 2 circuit is open or shorted - Heated Oxygen Sensor 1 Bank 2 circuit electrical connection - Faulty Heated Oxygen Sensor 1 Bank 2

When Detected

The closed loop control function for bank 1 does not operate even when vehicle is driving in the specified condition, the closed loop control function for bank 2 does not operate even when vehicle is driving in the specified condition.

Description

The Engine Control Module (ECM) performs ON/OFF duty control of the Air Fuel Ratio (A/F)/Heated Oxygen Sensor 1 heater corresponding to the engine operating condition to keep the temperature of Air Fuel Ratio (A/F)/Heated Oxygen Sensor 1 element at the specified range.