General Information

Engine Control
P0057 HO2S Heater Control Circuit Low (Bank 2 / Sensor 2) - General Information

Component Location





General Description

The normal operating temperature of the HO2S(Heated Oxygen Sensor) ranges from 350 to 850°C(662 to 1562°F). The HO2S heater greatly decreases the amount of time required for fuel control to become active. The PCM provides a pulse width modulated control circuit to adjust current through the heater. When the HO2S is cold, the value of the resistance is low and the current in the circuit is high. On the contrary, if the temperature in the resistor of the sensor rises, the current drops gradually.

DTC Description

If the PCM detects short to ground or open in heater under detecting conditions, PCM sets P0057.

DTC Detecting Condition





Specification





Diagnostic Circuit Diagram





Signal Waveform & Data
























Fig.1) The Normal data of HO2S heaters at idle.
Fig.2) The data of HO2S heaters at open condition in HO2S(B2S1) circuit (0A)
Fig.3) The signal waveforms of front HO2S(the upper) and heater(the lower) at idle (chassis ground used)
Fig.4) The signal waveforms of front HO2S(the upper) and heater(the lower) at idle (sensor ground used)
Fig.5) The signal waveforms of rear HO2S(the upper) and heater(the lower) at idle (chassis ground used)
Fig.6) The signal waveforms of rear HO2S(the upper) and heater(the lower) at idle (sensor ground used)
The output voltage of front HO2S is changed continuously accroding to air/fuel ratio, PCM controls fuel amount based on this value. Preheating is necessary for HO2S normal operation. Therefore heater unit is installed in HO2S, PCM can control air/fuel ratio with the output signal of HO2S simultaneous with engine run by reducing preheating time. PCM controls heater with duty cycle. HO2S' power source is main relay and PCM operates heater by ground control.