P0242 indicates that the boost pressure sensor (sensor B) circuit is reporting a voltage higher than the expected range. This usually points to a short to power, a faulty sensor, or a wiring/connector issue that causes the ECM to read an excessively high signal.
The sensor itself may have an internal short or defect that drives its output voltage too high.
Damaged insulation or chafed wiring can cause the sensor signal line to contact a power source, raising the voltage seen by the ECM.
Poor contact can create abnormal resistance or leakage paths that bias the signal high.
If the turbocharger produces boost beyond the sensor's measurable range, the sensor may output its maximum voltage, triggering a high‑circuit code.
A malfunction inside the engine control module could misinterpret the sensor signal, but this is uncommon and should be considered only after other causes are ruled out.
No. Replacing the PCM is rarely needed for this code; the issue is almost always the boost sensor, its wiring, or connectors. PCM replacement should be considered only after those components have been tested and found good.
Yes. If the sensor signal line is shorted to power or has a corroded connector, repairing the wiring or connector often clears the code without part replacement.
Continued operation with an over‑boost condition or incorrect sensor data can lead to excessive boost, increased engine stress, and possible damage; it is advisable to diagnose and repair the issue promptly.