DTC P2271: O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 2 [11/2021 - ]: Procedure

1. Turn the ignition switch to OFF.
2. Check the heated oxygen sensor connector.

   Has water entered the connector?

   Result	Proceed to
   Yes (Completely remove any water inside.)	A
   No	B

Result: 

A 

COMPLETELY REMOVE ANY WATER INSIDE 

Result: 

B 

See step  2

1. Disconnect the connector from ECM.
2. Disconnect the connector from the heated oxygen sensor.
3. Measure the resistance of harness between ECM connector and heated oxygen sensor connector.

   Connector & terminal

   B1-14 (RO2SR+) - B14-3

   B1-15 (RO2SR-) - B14-4

   Is the resistance less than 1 Ω?

   Result	Proceed to
   Yes	A
   No (Repair the open circuit of harness between ECM connector and heated oxygen sensor connector.)	B

Result: 

B 

REPAIR HARNESS 

Result: 

A 

See step  3

1. Measure the resistance between the ECM connector and engine ground.

   Connector & terminal

   B1-14 (RO2SR+) - Engine ground

   Is the resistance 1 MΩ or more?

   Result	Proceed to
   Yes	A
   No (Repair the short circuit to ground in harness between ECM connector and heated oxygen sensor connector.)	B

Result: 

B 

REPAIR HARNESS 

Result: 

A 

See step  4

1. Check exhaust system parts.

   HINT: 

   Check the following items.

   • Looseness and improper fitting of exhaust system parts
   • Damage (crack, hole etc.) of parts
   • Damage (crack, hole etc.) between air fuel ratio sensor and heated oxygen sensor

   Is there any fault in exhaust system?

   Result	Proceed to
   Yes (Repair or replace faulty parts.)	A
   No (Replace the heated oxygen sensor.)	B

Result: 

A 

REPAIR OR REPLACE FAULTY PARTS 

Result: 

B 

REPLACE HEATED OXYGEN SENSOR. Refer to  REMOVAL [11/2021 - ]