P0135 · blink 23 – Oxygen Sensor Heater Circuit Malfunction

System: Engine control (EFI)
Dashboard light: Check engine light (MIL)
Check-engine blink code: 23
Applies to: 1KR-FE: M300 (Sirion export = JDM Boon M300S/M301S(4WD? see gaps) & Passo KGC10/KGC15). JDM-spec ECU not separately documented | K3-VE: M301 (Sirion 1.3 = JDM Boon M310S? / Passo QNC10)
Description: Oxygen Sensor Heater Circuit Malfunction
Detection / symptoms: Detection: 1.When an open wire or short is present in the oxygen sensor heater system,
Possible causes: Trouble area: 1.Open wire or short circuit for the oxygen sensor heater circuit 2.Oxygen sensor heater 3.EFI ECU
What to check: Checking points: NOTE • When this code is outputted concurrently with another code, carry out the check for that code first. 1.Is the signal from the oxygen sensor inputted to the EFI ECU? 2.Is the harness between the oxygen sensor and the EFI ECU normal? 3.Is the output of the oxygen sensor correct? (If there are n; Unit check B8-220: front O2 heater 7.0 ohm (+1.4/-0.7) @20C
Confidence: high (factory manual, export spec)

From the factory service material. Clear the code and test-drive to confirm it returns. Search all fault codes · Common problems · Warning lights