This code indicates that the engine control module (PCM) has lost its data communication with the exhaust gas temperature sensor located on Bank 1, Sensor 2. This sensor is typically a digitally communicating sensor (rather than a simple thermistor) that reports exhaust temperatures to the PCM over a serial data line. When communication is interrupted, the PCM cannot monitor exhaust temperature at that location, which may affect emissions system operation and aftertreatment diagnostics.
The sensor itself is the most common failure point. Internal electronics in the sensor can fail, preventing it from communicating on the data bus.
The sensor's connector or nearby wiring is exposed to high exhaust heat and road debris. Corroded pins, melted insulation, or broken wires interrupt the communication line.
A break, short to ground, or short to voltage on the serial data circuit between the sensor and the PCM will trigger this code. This may affect only this sensor or other devices on the same bus.
If the sensor's power or ground supply is interrupted due to a fuse, wiring fault, or splice issue, the sensor cannot power up and communicate.
Extremely rare. A failure of the PCM's transceiver circuit for this data line could prevent communication. This should only be considered after all wiring, power, ground, and sensor checks are exhausted.
In many cases the vehicle will still drive, but emissions monitoring and aftertreatment functions may be disabled. On diesel vehicles, DPF regeneration may not complete. It is best to have it diagnosed promptly.
Almost never. This code is caused by the sensor, its wiring, or its power/ground supply in the vast majority of cases. Replacing the PCM is a last resort and is usually an incorrect recommendation unless every other possibility has been definitively ruled out.
Bank 1 is the engine bank containing cylinder #1. Sensor 2 is the second exhaust gas temperature sensor in the exhaust stream on that bank, typically downstream of the catalytic converter or diesel particulate filter.
An exhaust leak itself does not directly cause a communication loss. However, excessive heat from a nearby exhaust leak can damage the sensor or its wiring harness over time, which can then trigger this code.