P1135 Diagnostic Code in 2001 Toyota Tacoma: Causes, Solutions & Fix Steps
I own a 2001 Toyota Tacoma with a 3.4L engine and am currently encountering the P1135 error code: 'Air/Fuel Sensor Heater Circuit Response' (Bank 1 Sensor 1). This fault code indicates an issue with the heater circuit of the oxygen sensor in Bank 1, Sensor 1. I do not have access to a service manual for this model. Can you please advise where I should look for diagnosis and what specific components or steps to check? What are the most common causes and practical solutions for resolving this P1135 code on a 2001 Toyota Tacoma?
For a 2001 Toyota Tacoma with P1135, the most common fix is to inspect and replace the upstream oxygen sensor (O2 sensor) on Bank 1, Sensor 1. Ensure you verify the wiring harness and connector for corrosion or damage before replacing. A faulty heater circuit in this sensor can trigger the code, so a new OEM or compatible upstream O2 sensor is typically required.