Code Definition

P1155 — Air/Fuel Sensor Heater circuit

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Lexus

About P1155

P1155 is a manufacturer-specific powertrain diagnostic trouble code recorded for Lexus vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1155 is stored, the module has detected a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1155 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Bank 2 air fuel ratio sensor on this Lexus contains an internal heater that brings the sensor element up to operating temperature quickly so the Engine Control Module (ECM) can begin closed loop fuel control on that bank. The ECM controls and monitors the heater circuit current. DTC P1155 sets when the ECM detects that the air fuel ratio sensor heater circuit on Bank 2 Sensor 1 is not drawing the expected current or is out of range, indicating an open, short, or high resistance heater circuit. When the code is stored the Bank 2 sensor may take too long to reach temperature, delaying closed...

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