What is Case CX210C Fault Code 117?

Case CX210C Fault Code 117 indicates a malfunction in the Engine Coolant Temperature (ECT) Sensor circuit, specifically reporting an abnormally high voltage signal to the Engine Control Module (ECM). This diagnostic trouble code (DTC) triggers when the ECM detects a voltage reading above the manufacturer's specified threshold, typically indicating an open circuit, damaged sensor, or wiring issue.

The ECT sensor plays a critical role in the CX210C's Isuzu engine management system by monitoring coolant temperature and sending real-time data to the ECM. This information directly affects fuel injection timing, idle speed control, and engine protection protocols. When Code 117 is active, the ECM may default to a predetermined temperature value, potentially causing inefficient combustion, increased emissions, and compromised engine protection against overheating.

Common Symptoms

• Check Engine light or warning lamp illuminated on the instrument cluster
• Engine running in cold-start mode continuously, resulting in rough idle and black smoke
• Difficulty starting when the engine is warm due to incorrect fuel mapping
• Cooling fan running constantly at high speed regardless of actual engine temperature
• Reduced engine performance or power derate in some cases to protect components

Potential Causes

The most common technical causes for Code 117 on used CX210C excavators include:

• Open circuit in the ECT sensor wiring harness, often caused by wire chafing near the engine block or cylinder head
• Failed ECT sensor with internal circuit breakdown (common after 5,000+ operating hours)
• Corroded or loose connector pins at the sensor or ECM connection points—especially prevalent in machines exposed to moisture
• Damaged harness insulation from heat exposure near exhaust components or rubbing against metal edges
• Rare: ECM internal fault affecting the sensor signal processing circuit

How to Troubleshoot and Fix Code 117

Step 1: Visual Inspection Locate the ECT sensor on the engine block (typically near the thermostat housing on Isuzu engines). Inspect the wiring harness from sensor to ECM for visible damage, melting, or wear points where the harness contacts metal surfaces—a common issue in used excavators.

Step 2: Connector and Resistance Testing Disconnect the ECT sensor connector and inspect for corrosion, bent pins, or moisture. Using a digital multimeter, measure the sensor's resistance. At room temperature (68°F/20°C), resistance should read approximately 2,000-3,000 ohms. Compare readings to Case specifications for your exact engine variant.

Step 3: Circuit Voltage Check With the sensor disconnected and ignition on (engine off), measure voltage at the harness connector. You should see approximately 5 volts reference voltage from the ECM. No voltage indicates a wiring break or ECM issue. Full battery voltage (12V+) suggests a short to power.

Step 4: Harness Continuity Test Check continuity between the sensor connector and ECM pins using wiring diagrams. On used machines, pay special attention to harness routing near moving components or heat sources where insulation degrades over time.

Step 5: Component Replacement If testing confirms sensor failure, replace the ECT sensor with OEM or quality aftermarket parts. After replacement, clear codes using Case diagnostic software or a compatible scan tool and verify proper operation.

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Disclaimer: This guide provides general troubleshooting information. Always consult the Case CX210C service manual and consider professional diagnostic assistance for complex electrical issues or if unfamiliar with heavy equipment systems.