Kobelco SK480LC-8 Fault Code P0108: Complete Diagnostic Guide

What is Kobelco SK480LC-8 Fault Code P0108?

Fault Code P0108 indicates a Manifold Absolute Pressure (MAP) Sensor Circuit High Input voltage condition in the Kobelco SK480LC-8 excavator's engine control system. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormally high voltage signal from the MAP sensor, typically exceeding 4.5-4.9 volts for longer than the calibrated time threshold.

The MAP sensor is critical for the SK480LC-8's Hino J05E diesel engine performance, as it continuously monitors intake manifold pressure to calculate optimal fuel injection timing and air-fuel ratios. When this sensor reports incorrect high-pressure readings, the ECM cannot accurately manage combustion efficiency, potentially causing reduced power output, increased emissions, and compromised fuel economy. This is particularly problematic in high-demand applications where precise engine load calculations are essential for maintaining hydraulic system performance.

Common Symptoms

Operators of used SK480LC-8 excavators experiencing Code P0108 typically notice:

• Check Engine Light (CEL) illuminated on the instrument cluster with potential derate mode activation
• Noticeable power loss during digging operations or when lifting heavy loads
• Black smoke emission from the exhaust due to overfueling conditions
• Rough idle or unstable engine RPM, especially during warm-up cycles
• Poor throttle response when attempting to increase engine speed under load

Potential Causes

The most common technical reasons for P0108 on used SK480LC-8 machines include:

• MAP sensor internal failure causing stuck-high voltage output (common after 6,000+ operating hours)
• Damaged or corroded wiring harness between the MAP sensor and ECM, particularly at connector C-138 near the firewall
• Shorted 5-volt reference circuit within the sensor harness creating false high readings
• Vacuum hose disconnection or blockage preventing accurate manifold pressure measurement
• ECM internal fault in the sensor input circuit (rare but documented in pre-2012 production units)
• Moisture intrusion in electrical connectors due to damaged cab floor seals common in used machines

How to Troubleshoot and Fix Code P0108

Step 1: Visual Inspection and Preliminary Checks Begin by locating the MAP sensor on the intake manifold (passenger side of the Hino J05E engine). Inspect the sensor connector for corrosion, bent pins, or moisture—common issues in used excavators exposed to harsh environments. Check all vacuum hoses connected to the sensor for cracks, disconnections, or blockages. In older SK480LC-8 units, harness chafing often occurs where the wiring passes near the engine mount bracket.

Step 2: Electrical Testing with Diagnostic Tools Using a digital multimeter (DMM), perform a voltage check at the MAP sensor connector with the ignition on, engine off (KOEO). The 5-volt reference wire (typically gray wire at pin 1) should read 4.9-5.1 volts. The ground circuit (black wire) should show less than 0.1 volts resistance to battery negative. The signal wire (usually blue/white at pin 3) should read approximately 0.5-1.0 volts at key-on. If signal voltage reads above 4.5 volts with the engine off, the sensor is likely failed internally or the signal wire is shorted to the reference voltage.

Step 3: Sensor Replacement and Verification For used excavators, never assume a new sensor will fix the issue without testing the harness first. Disconnect the MAP sensor and measure resistance between the signal wire and ground—it should read infinite (open circuit). If you measure continuity, trace and repair the short in the harness. If harness testing confirms integrity, replace the MAP sensor with a genuine Hino part (P/N: 079800-5960) or verified OEM equivalent. After installation, clear codes using Kobelco diagnostic software (CAPS-II) or a compatible J1939 scanner, then perform a test cycle under load to verify repair.

Important: For excavators with over 8,000 operating hours, inspect the intake manifold gaskets and EGR system components, as vacuum leaks can create erratic MAP sensor readings that may trigger this code intermittently even with a functional sensor.

---

Disclaimer: This guide provides general troubleshooting information for Code P0108. Always consult the official Kobelco service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues. Improper repairs may void warranties or cause additional damage.