Subaru 2009 IMPREZA Service Manual page 1538

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
15 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
keep the engine speed at 3,000 rpm. (2 minutes
maximum)
2) Read the data of rear oxygen sensor signal
using Subaru Select Monitor or general scan
tool.
NOTE:
• Depress the clutch pedal. (MT model)
• Subaru Select Monitor
For detailed operation procedures, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOTC)(diag)-34, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
16 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
rapidly reduce the engine speed from 3,000
rpm.
2) Read the data of rear oxygen sensor signal
using Subaru Select Monitor or general scan
tool.
NOTE:
• Depress the clutch pedal. (MT model)
• Subaru Select Monitor
For detailed operation procedures, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOTC)(diag)-34, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
17 CHECK REAR OXYGEN SENSOR CONNEC-
TOR AND COUPLING CONNECTOR.
18 CHECK FRONT OXYGEN (A/F) SENSOR
AND REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), then
keep the engine idling for 5 minutes or more.
2) Read the data of rear oxygen sensor signal
using Subaru Select Monitor or general scan
tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedures, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4DOTC)(diag)-34, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Check
Is the voltage 490 mV or more? Go to step 16.
Is the voltage 250 mV or less? Go to step 18.
Has water entered the connec-
tor?
Is a voltage of 0.8 V or more
maintained for 5 minutes or
more?
EN(H4DOTC)(diag)-317
ENGINE (DIAGNOSTICS)
Yes No
Go to step 17.
Go to step 17.
Completely Go to step 19.
remove any water
inside.
Replace the front Go to step 19.
oxygen (A/F) sen-
sor. <Ref. to
FU(H4DOTC)-48,
Front Oxygen (A/F)
Sensor.>