What is Volvo Excavator Fault Code 128PID105SE2507-2?

Fault Code 128PID105SE2507-2 indicates an intermittent signal error from the Intake Manifold Air Pressure Sensor (Boost Pressure Sensor) on Volvo excavators. This diagnostic trouble code (DTC) specifically refers to PID 105 (Intake Manifold Pressure) with SPN 2507 and FMI 2, signaling that the Engine Control Module (ECM) is receiving erratic or unstable voltage readings from the boost pressure sensor circuit.

This sensor is critical for proper engine performance because it monitors the air pressure in the intake manifold after the turbocharger. The ECM uses this data to optimize fuel injection timing, air-fuel ratio, and turbocharger control. When intermittent signals occur, the engine management system cannot accurately regulate combustion, leading to reduced power output, increased emissions, and potential engine protection modes.

Common Symptoms

When this fault code is active, operators typically experience:

• Intermittent engine derate or loss of power, particularly under load or during acceleration
• Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL) illuminated on the dashboard
• Rough idling or hesitation during throttle response
• Black or gray exhaust smoke due to improper fuel-air mixture calculations
• Turbocharger underperformance with reduced boost pressure during operation

Potential Causes

The most common technical reasons for this code on used Volvo excavators include:

• Corroded or loose electrical connectors at the boost pressure sensor or ECM harness connections
• Damaged wiring harness with chafing or rubbing against engine components (common near the intake manifold mounting area)
• Failing boost pressure sensor with internal circuit degradation from heat cycling and age
• Contaminated sensor ports clogged with oil vapors, carbon deposits, or debris from the intake system
• Poor ground connections in the sensor circuit causing voltage fluctuations
• ECM software issues requiring calibration updates (less common but possible on older machines)

How to Troubleshoot and Fix Code 128PID105SE2507-2

Step 1: Visual Inspection Begin by thoroughly inspecting the boost pressure sensor located on the intake manifold. Check the electrical connector for corrosion, moisture, or damaged pins. Examine the wiring harness from the sensor to the ECM for signs of abrasion, especially where it contacts hot engine surfaces or sharp edges—a known wear point on used excavators.

Step 2: Electrical Testing Using a digital multimeter, perform voltage and resistance checks. With the ignition on (engine off), verify the 5-volt reference voltage from the ECM to the sensor. Check ground continuity (should be less than 1 ohm). Wiggle the harness while monitoring voltage to replicate the intermittent condition. Compare readings against Volvo specifications (typically 0.5-4.5V signal range).

Step 3: Sensor and Port Inspection Remove the boost pressure sensor and inspect the sensing port for carbon buildup or oil contamination. Clean the port with appropriate solvent and compressed air. Test the sensor's resistance across terminals (typically 1,000-3,000 ohms at room temperature). If readings are erratic or out of specification, replace the sensor.

Step 4: Advanced Diagnostics Connect Volvo VCADS (Volvo Computer Aided Diagnostic System) or compatible diagnostic software to monitor live sensor data. Observe the pressure readings during engine operation—values should change smoothly with throttle input. Erratic spikes or dropouts confirm sensor or wiring issues.

For used excavators specifically, pay extra attention to connector seal integrity and harness routing. Years of vibration and heat cycles often cause microscopic cracks in wiring insulation or connector housings that create intermittent faults.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Volvo service manual for your specific model and serial number. Complex electrical diagnostics should be performed by qualified technicians with proper diagnostic equipment. Incorrect repairs may cause further damage or safety hazards.