What is Kobelco SK460-8 Fault Code P0108?

Fault Code P0108 indicates a Manifold Absolute Pressure (MAP) Sensor Circuit High Input condition. This diagnostic trouble code is triggered when the Engine Control Module (ECM) detects a voltage signal from the MAP sensor that exceeds the normal operating range (typically above 4.5-4.8 volts).

The MAP sensor is critical for the Kobelco SK460-8's Hino J05E or J08E diesel engine performance. It measures intake manifold pressure and sends this data to the ECM, which uses it to calculate proper fuel injection timing, air-fuel ratio, and turbocharger boost control. When P0108 activates, the ECM cannot accurately determine engine load, leading to reduced power output and potential engine protection modes.

Common Symptoms

When P0108 is active on your SK460-8, you may experience:

• Check Engine Light (CEL) illuminated on the instrument panel with immediate power reduction
• Engine derate mode engaging, limiting maximum RPM to approximately 1800-2000 RPM
• Black smoke from the exhaust due to over-fueling from incorrect air calculations
• Poor throttle response and sluggish hydraulic function during heavy digging operations
• Rough idling or hesitation during acceleration, particularly under load

Potential Causes

The most common technical reasons for P0108 on used SK460-8 excavators include:

• Failed MAP sensor due to internal component degradation or contamination from oil vapor in older machines
• Damaged wiring harness between the MAP sensor and ECM, especially at known rub points near the engine mount brackets
• Corroded or loose connectors at the sensor (common on machines operating in coastal or high-humidity environments)
• Shorted signal wire to battery voltage or 5-volt reference circuit
• Clogged intake system causing abnormally high manifold pressure readings
• ECM internal fault (rare, but possible on high-hour machines with previous electrical issues)

How to Troubleshoot and Fix Code P0108

Step 1: Visual Inspection Locate the MAP sensor on the intake manifold near the turbocharger outlet. Inspect the three-wire connector for corrosion, moisture, or damaged pins. On used excavators, check for harness wear where cables contact the engine block or vibration points. Clean connectors with electrical contact cleaner and dielectric grease.

Step 2: Electrical Testing Using a digital multimeter (DVOM), backprobe the MAP sensor connector with the key on, engine off. Check the 5-volt reference wire (typically reads 4.8-5.2V), ground circuit (should be less than 0.1V to chassis ground), and signal wire (typically 0.5-1.5V at idle). If signal voltage reads above 4.5V with the engine off, suspect a shorted signal wire or failed sensor.

Step 3: Sensor Replacement and Verification If electrical values are abnormal, replace the MAP sensor with a genuine Hino or OEM-equivalent part. Clear codes using diagnostic software (Kobelco EMBOS or generic J1939 scan tool). Test drive under load and monitor live data to confirm signal voltage stays within 0.5V-4.5V range during operation.

Critical for Used Equipment: Before replacing the MAP sensor, verify the intake system is not restricted and check for vacuum leaks or damaged intake piping that could cause false high-pressure readings.

---

Disclaimer: This guide provides general diagnostic information. Always consult the official Kobelco service manual and consider professional diagnosis for complex electrical issues or if you lack proper diagnostic equipment.