1.CHECK CURRENT DATA.
1) Read the data of “Catalyst Temperature #12” using the Subaru Select Monitor or a general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedures, refer to “READ CURRENT DATA FOR ENGINE”. 
• General scan tool
For detailed operation procedures, refer to the general scan tool operation manual.
2) Start the engine and race it several times so that the engine speed exceeds 3,000 rpm.
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Does the data of “Catalyst Temperature #12” change?
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Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.
NOTE:
In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
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2.CHECK FOR POOR CONTACT.
Check for poor contact of ECM connector and exhaust temperature sensor 2 connector.
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Is there poor contact of ECM connector or exhaust temperature sensor 2 connector?
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Repair the poor contact of ECM connector or exhaust temperature sensor 2 connector.
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3.CHECK HARNESS BETWEEN ECM AND EXHAUST TEMPERATURE SENSOR 2 CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM and exhaust temperature sensor 2.
3) Measure the resistance of harness between ECM connector and exhaust temperature sensor 2 connector.
Connector & terminal
(B135) No. 35 — (E86) No. 1:
(B135) No. 13 — (E86) No. 2:
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Is the resistance less than 1 Ω?
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Repair the harness and connector.
NOTE:
In this case, repair the following item:
• Open circuit in harness between ECM connector and exhaust temperature sensor 2 connector
• Poor contact of coupling connector
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4.CHECK HARNESS BETWEEN ECM AND EXHAUST TEMPERATURE SENSOR 2 CONNECTOR.
1) Connect all connectors.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connector and chassis ground.
Connector & terminal
(B135) No. 35 (+) — Chassis ground (−):
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Is the voltage 5 V or more?
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Repair the short circuit to power supply in harness between ECM connector and exhaust temperature sensor 2 connector.
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Replace the exhaust temperature sensor 2. 
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