Code Definition

P042A — Catalyst temperature sensor signal error bank 1 sensor 2

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

About P042A

P042A 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 P042A 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 P042A 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 P042A fault code is set when the Engine Control Module (ECM) detects an error in the signal from the catalyst temperature sensor for Bank 1, Sensor 2. This code indicates a problem with the sensor's ability to accurately measure the temperature of the exhaust gases passing through the catalytic converter in Bank 1. The catalyst temperature sensor is critical for monitoring the operating temperature of the catalytic converter, which is vital for efficient emission control and preventing damage to the converter. A signal error from this sensor can affect the ECM’s ability to regulate emiss...

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