Code Definition

P242D — Exhaust Gas Temperature Sensor 3 Circuit High Voltage

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

About P242D

P242D 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 P242D is stored, the module has detected a signal or supply voltage higher than the expected operating range; 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 P242D 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 Engine Control Module monitors the exhaust gas temperature (EGT) sensor 3 signal to protect the exhaust aftertreatment components, particularly around the diesel particulate filter and catalyst. DTC P242D sets when the ECM detects a voltage from EGT sensor 3 that is higher than the calibrated maximum for a set period. Because these sensors are thermistors, a high signal voltage corresponds to an implausibly low exhaust temperature and typically indicates an open circuit, high resistance, or a short to reference voltage in the sensor signal or ground circuit. When set, the ECM may disable o...

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