01 How to Fix an Engine That Cuts Out and Restarts While Drivi… • 02 Eco-Friendly and Powerful: The Best Fuel-Efficient SUVs for… • 03 This Is Why Your Car’s Exhaust Smells Like Sulfur • 04 How Old Fuel Can Harm Your Engine and What to Do About It • 05 How to Tell If You Need Wheel Balancing • 06 C0050 - Right Rear Wheel Speed Circuit Malfunction • 07 10 Crucial Insights into Oxygen Sensors, Common Problems, a… • 08 P0105 - MAP Sensor Circuit Insufficient Activity • 09 C0080 and C0085 - Left Rear ABS Solenoid #1&#2 Circuit Malf… • 10 P0035 Turbo charger bypass valve control circuit high •

DTC codes / Volkswagen codes / P1555

P1555 · VolkswagenCharge Pressure Upper Limit Exceeded

P1555 on a Volkswagen means the engine control module has detected that actual charge pressure from the turbocharger has risen above the maximum limit it expects for the current operating conditions. The computer compares the manifold pressure sensor signal against a calculated ceiling and stores this code when the measured boost exceeds that ceiling for a calibrated period.

SystemPowertrain
Code typeVolkswagen specific
SeverityMedium
Fix difficultyIntermediate
AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

  • The engine warning light illuminates, often with no other noticeable change in vehicle behavior.
  • A sudden loss of power or limp mode when accelerating hard, as the ECU cuts boost to protect the engine.
  • Rough running or hesitation under load, particularly during overtaking or uphill driving.
  • A noticeable whistling or fluttering noise from the turbocharger area under acceleration.
  • Reduced fuel economy because the ECU may default to a rich, low-boost strategy.
  • In some cases, the engine may enter a reduced-power mode immediately after the code sets.

Common causes, most likely first

  1. A sticking or failed turbocharger wastegate actuator or variable-vane mechanism, preventing the ECU from bleeding off excess boost.
  2. A faulty charge pressure sensor (manifold absolute pressure sensor) sending an inflated pressure reading to the ECU.
  3. A kinked, blocked, or disconnected wastegate control hose, causing the wastegate to stay closed and boost to climb unchecked.
  4. A malfunctioning boost control solenoid valve (N75) that fails to command the wastegate to open.
  5. A restricted or collapsed intercooler or charge pipe, creating a pressure spike upstream of the restriction.
  6. A software calibration issue in the ECU that is slow to react to rising boost, especially on tuned or modified vehicles.
  7. A damaged turbocharger compressor wheel or housing that produces erratic boost beyond the control range.

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data to confirm when P1555 set and what boost pressure was reported at the time.
  2. Visually inspect all charge air hoses, intercooler connections, and the wastegate control line for kinks, cracks, or disconnections.
  3. Test the wastegate actuator with a hand vacuum pump to verify it moves freely and holds vacuum without leaking.
  4. Check the boost control solenoid (N75) for correct resistance and operation using a scan tool output test or a known-good substitute.
  5. Compare the charge pressure sensor reading with a mechanical boost gauge to rule out a sensor that over-reports pressure.
  6. Inspect the turbocharger compressor and turbine for damage or carbon buildup on variable-vane mechanisms, cleaning or replacing as needed.
  7. After repairs, clear the code and perform a road test with live boost data to confirm actual pressure stays within the commanded limit.

What a boost spike really tells you

  • A sticking wastegate is the most common root cause on Volkswagen turbo engines, yet many technicians replace the turbocharger before testing the actuator and its control circuit.
  • The charge pressure sensor can fail in a way that reports higher-than-actual pressure, causing the ECU to set P1555 even when the turbo is behaving correctly.
  • A restricted intercooler or collapsed charge pipe can create a pressure spike that the sensor sees as overboost, so always inspect the intake tract before condemning the turbo.
  • On tuned or modified Volkswagens, an aggressive ECU calibration can command boost levels that exceed the factory upper limit, setting P1555 without any hardware fault.
  • P1555 does not always mean the turbo is overboosting mechanically; a faulty N75 solenoid or a leaking wastegate diaphragm can produce the same code by preventing proper boost control.

Can I keep driving with P1555?

You can drive the vehicle gently to a repair shop, but avoid hard acceleration and high-load situations because repeated overboost can damage the turbocharger or engine. If the car enters limp mode, keep speeds low and have it checked promptly.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Volkswagen vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage