Code Definition

P0426 — Catalyst temperature sensor circuit malfunction bank 1 sensor 1

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

About P0426

P0426 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 P0426 is stored, the module has detected 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 P0426 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 P0426 when it detects an electrical malfunction in the circuit of the catalyst temperature sensor (Bank 1, Sensor 1). This sensor monitors exhaust gas temperature before the catalytic converter to ensure optimal emissions performance. The fault may be triggered by an out-of-range voltage signal, open/short circuits, or sensor failure.

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