Code Definition

P0428 — Catalyst temperature sensor circuit high bank 1 sensor 1

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0428

P0428 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0428 is stored, the module has detected a signal or supply voltage higher than the expected operating range; a bank-specific fault, meaning it applies only to one cylinder bank of a multi-bank engine; and 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.

Because P0428 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The powertrain control module (PCM) sets P0428 when it detects that the voltage signal from the catalyst temperature sensor (Bank 1, Sensor 1) is higher than the expected range. This sensor monitors exhaust gas temperature before the catalytic converter to ensure optimal emissions control. A high signal typically indicates an electrical issue, sensor failure, or abnormal exhaust temperature readings.

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