Subaru 2009 IMPREZA Service Manual page 619

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
3 CHECK WAVEFORM DATA ON THE SUBA-
RU SELECT MONITOR (WHILE IDLING).
1) Run the engine at idle.
2) In the condition of step 1), use the Subaru
Select Monitor to read the waveform data.
• At normal condition
1
REAR OXYGEN
SENSOR VOLTAGE
(V)
0
10 sec/div
• At abnormal condition 1 (numerous inversion)
1
REAR OXYGEN
SENSOR VOLTAGE
(V)
0
10 sec/div
• At abnormal condition 2 (noise input)
1
REAR OXYGEN
SENSOR VOLTAGE
(V)
0
10 sec/div
4 CHECK CATALYTIC CONVERTER.
5 CHECK REAR OXYGEN SENSOR CONNEC-
TOR AND COUPLING CONNECTOR.
Check
Is a normal waveform dis-
played?
EN-06668
EN-06669
EN-06670
Is the catalytic converter dam-
aged?
Has water entered the connec-
tor?
EN(H4SO)(diag)-202
Yes No
Go to step 4. • The waveform is
displayed at abnor-
mal condition 1:Go
to step 4.
• The waveform is
displayed at abnor-
mal condition 2:Go
to step 5.
Replace the cata- Go to step 5.
lytic converter.
<Ref. to
EC(H4SO)-3,
Front Catalytic
Converter.>
Completely Go to step 6.
remove any water
inside.