Diagnostic article Generic OBD-II
P0BCE: ISG U-phase temperature-sensor low input
The documented Mazda P0BCE procedure covers iSG U-phase temperature-sensor low input.
Read before applying this article
Documented application
Mazda3 workshop manual 01/2019 onward, d9n1-1a-22d_ver10; INTEGRATED STARTER GENERATOR (ISG). Verify exact vehicle specification; this is a Mazda application example.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P0BCE generally identifies generator inverter temperature sensor A circuit low. Mazda's M Hybrid ISG maps this code specifically to its internal U-phase FET temperature sensor.
A sensor-limit fault is not a temperature diagnosis
The documented trigger is an input of 1.44 V or less for half a second. This electrical limit does not establish that the inverter is physically cold or that it has overheated. The same source separately identifies characteristic and high-input faults for that phase and corresponding codes for the other phases.
The component is internal to the ISG, and the factory cause list identifies an ISG malfunction. The diagnostic sequence nevertheless distinguishes present from historical records, rechecks after an ignition transition and assesses recurrence under the original operating conditions. Communication noise is noted as a possible influence on a displayed record.
Effects of losing trustworthy temperature information
Hybrid supply is stopped, leaving vehicle loads on the 12-volt battery, while i-stop, regeneration and motor assistance are inhibited. Mazda warns that continued operation can deplete that battery and prevent further driving.
Professional confirmation should retain the U-phase identity and any companion temperature-sensor codes. The voltage criterion is not an instruction to probe the internal FET circuitry or substitute a resistor. Use the exact ISG service procedure and safe data collection to establish recurrence before a supported assembly-level repair decision.
Documented application
Mazda3 workshop manual 01/2019 onward, d9n1-1a-22d_ver10; INTEGRATED STARTER GENERATOR (ISG). Verify exact vehicle specification; this is a Mazda application example. Mazda factory diagnostic page, mirrored by CHARM.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Generator Inverter Temperature Sensor A Circuit Low
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT