Subaru 2009 IMPREZA Service Manual page 1610

Diagnostic Trouble Code (DTC) Detecting Criteria
GENERAL DESCRIPTION
I: DTC P0038 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 2)
1. OUTLINE OF DIAGNOSIS
Detect the rear oxygen sensor heater open or short circuit.
The rear oxygen sensor heater performs duty control, and the output terminal voltage at ON is 0 V, and the
output terminal voltage at OFF is the battery voltage.
Judge as NG when the terminal voltage remains High.
2. COMPONENT DESCRIPTION
(A)
(B)
0V
(A) Battery voltage
(D) High error
3. ENABLE CONDITIONS
Secondary Parameters
Battery voltage
Elapsed time after engine starting
Engine speed
4. GENERAL DRIVING CYCLE
After starting the engine, perform the diagnosis continuously when engine is low speed.
(D) OFF
ON
(B) Output voltage of the rear oxygen
sensor heater
Enable Condition
10.9 V
1 second
< 8000 rpm
GD(H4DOTC)-22
(C)
(C) 256 milliseconds (cycles)
EN-01793