Sumitomo Excavator Fault Code P1113: Complete Diagnostic Guide

What is Sumitomo Fault Code P1113?

Fault Code P1113 indicates an Intake Air Temperature (IAT) Sensor Circuit High Voltage condition. This diagnostic trouble code triggers when the Engine Control Module (ECM) detects a voltage signal from the intake air temperature sensor that exceeds the manufacturer's specified range, typically above 4.5-4.8 volts.

The IAT sensor plays a critical role in Sumitomo excavator engine management by measuring the temperature of incoming air entering the combustion chamber. The ECM uses this data to calculate optimal fuel injection timing, air-fuel mixture ratios, and turbocharger boost pressure. When P1113 appears, the ECM typically defaults to a predetermined value, which can compromise fuel efficiency, engine power output, and emissions compliance—particularly problematic in used excavators operating under demanding job site conditions.

Common Symptoms

When Code P1113 is active, operators typically experience:

• Check Engine Light or malfunction indicator lamp illuminated on the instrument panel
• Reduced engine power or noticeable loss of hydraulic performance during high-demand operations
• Hard starting in cold weather conditions due to incorrect fuel mixture calculations
• Black smoke from exhaust indicating rich fuel mixture from compensated ECM programming
• Increased fuel consumption as the ECM operates without accurate air temperature data

Potential Causes

The most common technical causes for P1113 in Sumitomo excavators include:

• Open circuit in IAT sensor wiring harness—especially at flex points near the air intake manifold where vibration causes wire fatigue
• Failed IAT sensor with internal circuit breakdown (common in machines with 5,000+ operating hours)
• Corroded or damaged electrical connector at the sensor or ECM connection points due to moisture intrusion
• Damaged wiring insulation from rodent activity or contact with hot engine components
• Faulty ECM (rare, but possible in high-hour used equipment with exposure to electrical surges)

How to Troubleshoot and Fix Code P1113

Step 1: Visual Inspection Begin by locating the IAT sensor (typically integrated into the air intake manifold or air filter housing). Inspect the wiring harness for visible damage, chafing against metal surfaces, melted insulation, or loose connections. On used excavators, pay particular attention to connector corrosion—disconnect and examine pins for green oxidation or moisture.

Step 2: Electrical Testing Using a digital multimeter, disconnect the IAT sensor connector and measure resistance across the sensor terminals. At 68°F (20°C), resistance should typically read 2,000-3,000 ohms (consult your service manual for exact specifications). If the reading shows infinite resistance (open circuit), replace the sensor. Also check for continuity in the wiring harness from sensor to ECM.

Step 3: Voltage Circuit Check With the ignition on and sensor disconnected, measure reference voltage at the harness connector. You should see approximately 5 volts from the ECM. If voltage reads above 5 volts continuously, suspect wiring short to battery power or potential ECM malfunction.

Step 4: Clear and Retest After repairs, clear the fault code using diagnostic software compatible with Sumitomo systems. Run the machine through various operating temperatures and loads to confirm the code doesn't return.

For used excavators, always replace connectors when installing new sensors, as aged terminals create intermittent high-resistance connections that can retriggered the fault.

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