The normal operating temperature of the HO2S(Heated Oxygen Sensor) ranges 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 ECM 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, the temperature in the resistor of the sensor rises, the current drops gradually.
ECM sets DTC P0038 if the ECM detects that the rear HO2S heater control line is open or short to battery line.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Electrical Check | ● Open or short to battery in control harness ● Contact resistance in connectors ● Faulty HO2S |
Enable Conditions | ● 10V < Battery voltage < 16V ● 1.17% < Heater power < 98.83% | |
Threshold Value | ● Short to Battery or Line break | |
Diagnostic Time | ● 10 sec. | |
MIL On Condition | ● 2 Driving Cycles |
Temp.(°C) | Temp.(°F) | Heater Resistance (Ω) |
18~20 | 64~82 | Approx. 9 |
