Boost Calibration Fault
Your engine's turbocharger boost pressure isn't matching what the ECU expects, like a pressure gauge showing the wrong reading. The computer can't properly calibrate how much air to force into the engine.
The ECU monitors boost pressure via the MAP (Manifold Absolute Pressure) or turbo boost sensor and compares it against expected values based on throttle position and engine load. If measured boost deviates significantly from calibrated values, a fault is triggered. The ECU uses this data to adjust fuel injection and ignition timing for optimal turbo performance.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Boost Pressure | Within ±5% of expected calibration curve | Deviation >10% from expected values or sensor signal out of range |
| Sensor Signal Voltage | 0.5–4.5V (varies by sensor type) | <0.2V or >4.8V, indicating sensor malfunction |
Code P1305 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1305 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.