What is Komatsu PC160LC-7 Fault Code E116?

Fault Code E116 on the Komatsu PC160LC-7 indicates a malfunction in the engine coolant temperature sensor circuit. This Diagnostic Trouble Code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormal voltage signal from the coolant temperature sensor, typically indicating an open circuit, short circuit, or sensor degradation.

The coolant temperature sensor is critical for the PC160LC-7's SAA6D102E-2 engine management system. It provides real-time temperature data that the ECM uses to optimize fuel injection timing, adjust idle speed, control the cooling fan, and prevent engine overheating. When this sensor fails or sends erratic signals, the engine cannot properly regulate its thermal management, potentially leading to inefficient combustion, increased emissions, and risk of catastrophic engine damage on these workhorse hydraulic excavators.

Common Symptoms

• Check Engine Light or warning lamp illuminated on the instrument cluster
• Engine running in limp mode with reduced power output and limited RPM range
• Cooling fan running continuously at maximum speed, even when engine is cold
• Difficulty starting in cold conditions due to improper fuel enrichment
• Abnormal temperature gauge readings showing extreme hot or cold (pegged readings)

Potential Causes

On used Komatsu PC160LC-7 machines, this fault typically stems from age-related component degradation. The most common causes include:

• Failed coolant temperature sensor due to internal resistance drift or element corrosion after years of thermal cycling
• Damaged wiring harness at known rub points near the engine mounting brackets or along the valve cover where vibration causes insulation wear
• Corroded or loose electrical connectors at the sensor plug, especially on machines operated in marine or winter road salt environments
• ECM connector pin corrosion affecting the sensor signal circuit (typically Pin 38 on the 90-pin ECM connector)
• Coolant contamination causing sensor probe coating and inaccurate readings
• Previous repair attempts using incorrect sensor resistance specifications (should be approximately 2.45kΩ at 68°F/20°C)

How to Troubleshoot and Fix Code E116

Step 1: Visual Inspection Begin by locating the coolant temperature sensor on the thermostat housing of the SAA6D102E-2 engine (left side, near cylinder head). Inspect the two-wire connector for corrosion, bent pins, or moisture intrusion. On used excavators, check the entire wiring harness from sensor to ECM for chafing, especially where it passes near the alternator bracket and fuel injection pump.

Step 2: Electrical Testing Disconnect the sensor and measure resistance across the sensor terminals using a quality digital multimeter. Compare readings against Komatsu specifications (approximately 2.45kΩ at 68°F, decreasing to 0.30kΩ at 176°F). If resistance is out of specification or reads infinite/zero, replace the sensor with a genuine Komatsu part number 6732-81-3140. Also check for 5-volt reference signal at the connector with key on, engine off.

Step 3: Harness and ECM Verification If the sensor tests correctly, perform a continuity test on both wires from the sensor connector to the ECM connector (check for opens). Measure resistance to ground on the signal wire (should be infinite/open). On high-hour used machines, remove and inspect the ECM connector for green corrosion or pushed-back pins. Use electrical contact cleaner and apply dielectric grease during reassembly.

Step 4: Clear Code and Monitor After repairs, clear the fault code using Komatsu diagnostic software (KDPF) or a compatible scan tool. Run the engine through multiple thermal cycles and monitor live coolant temperature data to verify the repair.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu PC160LC-7 service manual and consider professional diagnostic assistance for complex electrical issues, especially when dealing with used equipment histories.