Both codes look to be related.

> P1135 Air/Fuel Sensor Heater Circuit Response (Bank 1 Sensor 1) 

> P1155 Air/Fuel Sensor Heater Circuit. (Bank 1 Sensor 2)

Source: [http://www.engine-light-help.com][1]


Replacing the sensor may fix the issue, but as pointed out in the answer to your previous question:

>it is not always the sensor that goes bad. Sensors read the mixture and efficiency of your combustion, and can trigger a code if you are running rich/lean.

Source: [https://mechanics.stackexchange.com/a/2880/1554][2]

Some additional information:<br/>
[http://www.justanswer.com/toyota/][3]<br/>
[http://wiki.answers.com][4]


  [1]: http://www.engine-light-help.com/toyota-check-engine-light.html
  [2]: https://mechanics.stackexchange.com/a/2880/1554
  [3]: http://www.justanswer.com/toyota/2t7kr-2002-toyota-sienna-obd-code-fuel-sensor-circuit-bank-sensor.html
  [4]: http://wiki.answers.com/Q/Where_is_the_sensor_for_an_OBD2_Code_error_P1155_for_a_Toyota_Sienna_2001._How_do_you_change_it_and_what_is_the_effect_if_you_do_not_change_it