P1135 Toyota Rav4 2.0 -

Question

Sensor 1 bank 1 has been changed twice with new toyota parts but keeps on coming back. Fuel consumption dropped to 26 mpg. @£188.00 a time  its getting expensive, what else can it be.

Answer 1

P1135 A/F sensor heater circuit malfunction Bank 1 Sensor 1

The A/F sensor is relay operated and is fuse protected, If the A/F has been replaced the problem is not with the A/F sensor, This is more a electrical problem , For start replace the relay regardless if you think it works, Some shop replace the A/F  relay as a safe guard when a P1135 is set. The relay is located in the engine /fuse relay box listed as A/F relay and also check the fuse for this  A/F sensor listed as A/F