P0039 indicates the Engine Control Module has detected that the voltage range for the turbo/supercharger bypass valve control circuit is outside its expected limits, meaning the valve may be stuck open or closed.
The valve can fail mechanically or its internal coil can short/open, causing voltage outside the normal range.
Damage to the connector pins, pinched wires, or exposure to heat can cause high resistance or shorts.
A poor ground or loss of reference voltage will shift the sensed voltage range.
The PCM’s driver transistor can fail, but this is less common than valve or wiring problems.
Yes, but it is rare. Most cases are due to a bad bypass valve, wiring, or grounding issue. Replacing the PCM should be a last resort after confirming the valve and circuit are functional.
Resetting only clears the stored fault. If the underlying fault remains, the code will reappear after the vehicle completes a drive cycle.
The vehicle will likely run with reduced boost, resulting in lower power and possible fuel‑economy penalties. It is generally safe for short distances, but prolonged driving can cause further wear on the turbo/supercharger and may increase emissions.
It refers to the measured voltage being outside the calibrated minimum or maximum limits set by the manufacturer, indicating the control circuit is not responding correctly.