What is Kobelco SK200-8 Fault Code P0108?

Fault Code P0108 on the Kobelco SK200-8 excavator indicates a Manifold Absolute Pressure (MAP) Sensor Circuit High Input condition. 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 volts for a specified duration.

The MAP sensor is a critical component in the engine management system that monitors intake manifold pressure and air density. On the SK200-8's Hino J05E diesel engine, this sensor provides essential data to the ECM for calculating proper fuel delivery, injection timing, and turbocharger boost control. When the sensor reports implausible high values, the ECM cannot accurately manage combustion efficiency, leading to performance degradation and potential engine damage if left unaddressed.

Common Symptoms

When Code P0108 is active on your SK200-8, you may experience:

• Check Engine Light or malfunction indicator lamp illuminated on the dashboard
• Noticeable loss of engine power and reduced hydraulic system responsiveness during digging or lifting operations
• Rough idle or irregular engine RPM fluctuations, especially during warm-up
• Black smoke from the exhaust due to overfueling conditions caused by incorrect air density calculations
• Engine derate mode activation, limiting maximum RPM to protect the powertrain

Potential Causes

Several factors can trigger P0108 on used Kobelco SK200-8 excavators:

• Failed MAP sensor with internal short circuit or contamination from oil vapor or debris
• Damaged or corroded wiring harness between the MAP sensor and ECM, particularly at connection points near the engine valve cover where vibration and heat cycling are severe
• Shorted signal wire creating a direct path to the 5-volt reference voltage
• Faulty ECM connections or corrosion at the ECM connector pins (common in machines operating in wet or corrosive environments)
• Vacuum line issues (if equipped) causing false pressure readings, though less common on this model
• ECM internal fault affecting the sensor circuit processing (rare but possible in high-hour machines)

How to Troubleshoot and Fix Code P0108

Step 1: Visual Inspection Begin with a thorough inspection of the MAP sensor located on the intake manifold near the turbocharger outlet. Check for physical damage, oil contamination, or loose mounting. Inspect the three-wire connector for corrosion, bent pins, or moisture intrusion—especially critical on used excavators where environmental exposure accelerates connector degradation.

Step 2: Electrical Testing Using a digital multimeter, perform voltage checks with the ignition on, engine off. The MAP sensor should receive approximately 5 volts on the reference wire and have a solid ground connection (less than 0.1 volts). Measure the signal wire voltage; readings consistently above 4.5 volts confirm the high input condition. Check for resistance between signal wire and ground with the sensor disconnected; infinite resistance is normal, while low resistance indicates a short circuit.

Step 3: Wiring Harness Evaluation On used SK200-8 machines, carefully trace the sensor harness from the MAP sensor to the ECM, checking for abrasion points where the harness contacts frame members or routing clips. Pay special attention to areas near the engine mount where vibration causes wire chafing. Use dielectric grease on all connections during reassembly to prevent future corrosion.

Step 4: Component Replacement and Verification If testing reveals a faulty sensor (most common), install a genuine Kobelco or OEM-equivalent MAP sensor and clear codes using Kobelco diagnostic software or a compatible scan tool. After replacement, perform a static test by monitoring sensor output at various simulated altitudes if your diagnostic tool allows, or conduct a road test under load to verify proper operation across the engine's operating range.

Disclaimer: This guide provides general troubleshooting information. For complex electrical diagnostics or if you're uncomfortable working with engine management systems, consult a certified Kobelco technician or qualified heavy equipment mechanic. Improper diagnosis can lead to unnecessary parts replacement or further damage.