Turbo Charge Relief Circuit Malfunction
Your turbocharger's waste gate valve (which releases excess boost pressure) isn't working properly, like a pressure relief valve stuck or not responding. The engine computer detected the turbo isn't maintaining correct boost levels.
The ECU monitors the turbo boost pressure and the waste gate control valve solenoid's response. It compares actual boost pressure against expected values based on throttle position and engine load. If the waste gate doesn't vent excess pressure as commanded, the ECU detects a malfunction.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Boost Pressure vs. Command | Within 0.5 PSI of target pressure | Boost pressure exceeds target by >1.5 PSI consistently |
| Waste Gate Solenoid Response | Solenoid activates/deactivates within 200ms | No response or delayed >500ms |
Code P1704 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, P1704 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.