What Does P1555 Mean?
The turbocharger or supercharger boost pressure has exceeded the maximum allowable limit programmed in the ECM. This indicates an overboost condition that could damage the engine.
Safety Warning
Do not drive aggressively. Overboost can cause severe engine damage including bent rods, blown head gasket, or piston failure. Reduce speed and seek immediate repair.
Common Causes
35%
Failed or stuck wastegate actuator allowing excessive boost
30%
Boost pressure control valve stuck closed or malfunctioning
15%
Restricted exhaust system causing backpressure and overboost
10%
Disconnected or split boost pressure hoses/intercooler pipes
10%
ECM software issue or aftermarket performance tune
Diagnostic Steps
1
Step 1: Inspect all boost pressure hoses and intercooler piping for damage, disconnections, or restrictions
2
Step 2: Monitor boost pressure with scan tool during test drive; note maximum pressure reached
3
Step 3: Test wastegate actuator operation using vacuum pump or scan tool actuator tests; verify full range of motion
4
Step 4: Inspect wastegate linkage for binding, damage, or disconnection
5
Step 5: Check boost control solenoid operation and verify proper vacuum signal routing
Estimated Repair Cost
$200 - $1,200
Parts + labor, varies by vehicle and location
The turbocharger or supercharger boost pressure has exceeded the maximum allowable limit programmed in the ECM. This indicates an overboost condition that could damage the engine.
The most common cause of P1555 (Charge Pressure Upper Limit exceeded) is: Failed or stuck wastegate actuator allowing excessive boost
Typical repair costs for P1555 range from $200 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Do not drive aggressively. Overboost can cause severe engine damage including bent rods, blown head gasket, or piston failure. Reduce speed and seek immediate repair.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1555 to identify the root cause.
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