P1555 is a manufacturer-specific OBD-II diagnostic trouble code. Because it is manufacturer-specific, its exact definition depends on the vehicle application, often relating to the turbocharger boost control system.
The exact application must be verified before diagnosis. The code indicates a detected condition in the relevant system, but testing is required to identify the root cause.
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Key Takeaways
- P1555 is a manufacturer-specific code, meaning its exact definition varies by automaker and vehicle application.
- On many Volkswagen, Audi, and Skoda applications, it indicates that the charge pressure has reached or exceeded the upper control limit.
- Possible causes include a stuck wastegate, a faulty boost control solenoid, or a vacuum leak.
- Diagnosis requires verifying the exact factory definition and testing the relevant turbocharger and boost control components.
P1555 Code Description and Implications
P1555 is a manufacturer-specific powertrain code. Because the second digit is “1”, the definition is controlled by the automaker rather than the SAE standardized list.
Some Volkswagen, Audi, and Skoda applications: P1555 indicates a “Charge Pressure Control: Upper Limit Reached” fault, commonly known as an overboost condition.
Certain other applications: P1555 may relate to different manufacturer-specific systems, such as cruise control or electronic throttle circuits.
When the control module detects this condition, it sets this trouble code. Because this is a manufacturer-specific code, the exact definition and diagnostic steps vary by automaker.
Common Causes of the P1555 Code
Possible causes depend entirely on the specific vehicle application.
For VAG overboost applications, causes include a wastegate that is stuck closed, a failing boost control solenoid, or restricted vacuum lines.
A faulty MAP sensor or boost pressure sensor providing incorrect readings can also trigger the code.
In rare cases, an internal control module fault or software calibration issue can cause improper boost regulation.
Symptoms Associated With P1555
The primary symptom is an illuminated check engine light.
Drivers may experience a sudden loss of power or limp mode if the engine control module detects overboost and reduces engine output.
Hesitation during hard acceleration or unusual turbocharger spooling noises may also occur.
Diagnosing the P1555 Trouble Code
Diagnosis must begin by confirming the exact factory definition for the specific make, model, and year.
For overboost applications, technicians inspect the turbocharger wastegate actuator and vacuum lines for proper movement and restrictions.
The boost control solenoid is tested for proper electrical operation and vacuum routing.
Live data is monitored to compare the actual boost pressure against the specified boost pressure during a test drive.
Repairing the P1555 Issue
Repairs follow the confirmed diagnosis for the specific application.
If a vacuum line is cracked or disconnected, replacing the line resolves the issue.
If the wastegate actuator is seized or the boost control solenoid fails testing, replacing the confirmed failed component is required.
If the MAP sensor provides erratic data, replacing the sensor restores accurate boost monitoring.
Cost Considerations for P1555 Repairs
Repair costs vary depending on the underlying fault and the vehicle application.
Replacing vacuum lines or a boost control solenoid involves standard parts and moderate labor.
If the repair requires replacing the turbocharger wastegate actuator or the turbocharger assembly itself, costs increase significantly.
Cost depends on diagnostic time, component accessibility, required parts, programming requirements, and labor.
Prevention Strategies for Future Occurrences
Inspecting turbocharger vacuum lines and boost control hoses during routine maintenance can help identify developing cracks or brittleness.
Ensuring the engine’s PCV system is functioning properly helps prevent excessive crankcase pressure from interfering with turbocharger actuation.
Troubleshooting Tips and Best Practices
Never assume a manufacturer-specific code has a universal meaning. Always verify the exact factory service information for your specific vehicle.
Do not replace the turbocharger without first verifying the boost control solenoid, vacuum lines, and wastegate actuator movement.
If P1555 is accompanied by underboost codes, suspect a boost leak or a wastegate stuck open rather than an overboost mechanical failure.
More OBD-II Codes
| P1519 | P1520 | P1524 | P1525 |
| P1529 | P1531 | P1565 | P1571 |
| P1574 | P1580 | P1586 | P1587 |
| P0299 | P0101 | P0171 | P0174 |
| P1403 | P1432 | P1444 | P1445 |
| P1446 | P1447 | P0300 | P0420 |
Frequently Asked Questions
Is P1555 a generic OBD-II code?
No. P1555 is a manufacturer-specific code, meaning its exact definition and diagnostic procedure depend entirely on the vehicle’s make, model, and application.
Can I drive my vehicle with a P1555 code?
It depends on the application. If it indicates an overboost condition, the vehicle may enter limp mode to protect the engine, limiting drivability.
Will a P1555 code cause engine damage?
Potentially. If severe overboost occurs and the control module fails to intervene by limiting fuel and spark, it could cause internal engine damage.
Does P1555 always mean the turbocharger is broken?
No. The code often points to a simple vacuum leak, a stuck wastegate actuator, or a failing boost control solenoid rather than a failed turbocharger.
How do I clear a manufacturer-specific P1555 code?
Clearing the code requires fixing the underlying mechanical, vacuum, or electrical fault. Simply using a scan tool to erase the code will not repair the root cause.
What Should You Do About the P1555 Code?
Confirm the exact factory definition for your specific vehicle, then follow the applicable manufacturer diagnostic procedure for the relevant system and components.
Because P1555 is manufacturer-specific, testing the exact sensors, solenoids, or mechanical components identified by the factory service information is required to find the root cause.
Once the fault is confirmed, perform the necessary repairs and verify the fix by clearing the codes and completing a test drive.
