Air/Fuel Ratio Sensor Heater Circuit Malfunction – P1155 Error Code -Toyota

Air/Fuel Ratio Sensor Heater Circuit Malfunction –

P1155 Error Code –




  • What’s means of error code P1155 – Toyota
  • Symptoms of error code P1155 – Toyota
  • Causes of error code P1155 – Toyota
  • Solutions for the resolve error code P1155

           Description of Error code P1155 

The PCM (powertrain control Module) requires accurate Air/Fuel mixture readings to optimize fuel economy as well as emissions. If and inaccurate reading is sent to the control module, the amount of fuel required may not be enough or may exceed the required. That’s why many current  model manufacture use Air /Fuel Sensor instead of conventional Oxygen Sensor. An Air/Fuel sensor can read in a wider and narrower range of fuel mixtures. The Air/Fuel sensor have a heater that helps them get the temperature needed for good performance. A dedicated circuit controls the heater and using a pulse models modulation, it regulates the Temperature of the sender, taking this action accurately. In Toyota cars, the PCM sends a reference signal corresponding to 3.0 volt to the Air/Fuel sensor.  A detection circuit within the PCM monitors the changes in current flow and produces and output voltage signal proportional to the Air/Fuel mixture. The setting of fault code P1155 obd2 for the manufacturers In Toyota indicates the the heater circuit of the Air/Fuel Ratio sensor 1 of bank 2 has experienced unstable operation The Air/Fuel sensor picture in Blow


        Symptoms of fault code P1155


  • The Check Engine light is on.
  • Difficult to start the Engine during high temperature.
  • The fuel loses performance.
  • instabilities during idling
  • Poor acceleration.
  • The engine power is reduced.


          Causes of Error code P1155


  1. The Diagnostic code P1155 is set because of the following reasons:
  2. Air/Fuel Sensor 1 circuit cables or connectors may be defective.
  3. Air/Fuel Ratio Sensor 1 control circuit connections may be shorted or have an open credit causing the malfunction.
  4. The Air/Fuel Sensor may be defective.


  •     Possible solutions of the error code P1155


The steps to solve the Error code P1155 are the following:

As a first step, we recommend you consult with Technical person of your car

Check for air leaks, especially near the installation of the Air/Fuel Ratio Sensor Also, check the electrical circuit components of this sensor for deficiencies due to burns, corrosion or other condition

perform voltage tests on the Air/Fuel Sensor circuit and verify that these are within the parameters set by the manufacturer.

If inconsistencies are found, make the proper corrections

Check the integrity of the A/F ratio sensor if you find that the sensor is damaged, replace it.

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