Komatsu PC210LC-7 Fault Code E317: Expert Diagnostic Guide

What is Komatsu PC210LC-7 Fault Code E317?

Fault Code E317 on the Komatsu PC210LC-7 indicates a malfunction in the hydraulic oil temperature sensor circuit, specifically detecting an abnormal voltage signal or open/short circuit condition in the sensor wiring.

This code triggers when the Engine Control Module (ECM) receives voltage readings outside the normal operating range (typically 0.5-4.5V) from the hydraulic oil temperature sensor. The PC210LC-7 relies heavily on accurate temperature monitoring to protect the hydraulic system from overheating, regulate pump flow compensation, and prevent component damage. When this sensor circuit fails, the machine cannot properly manage hydraulic system performance, potentially leading to reduced efficiency or catastrophic hydraulic component failure.

For this specific model, the hydraulic oil temperature sensor is critical because the variable displacement piston pump adjusts output based on oil temperature feedback to maintain optimal viscosity and system pressure.

Common Symptoms

• Warning light illumination on the monitor panel with "E317" displayed on the LCD screen
• Reduced hydraulic performance or sluggish operation, especially during cold starts when the ECM cannot verify safe operating temperature
• Automatic derate mode engaging prematurely, limiting engine RPM and hydraulic flow
• Erratic temperature gauge readings that fluctuate wildly or show constant maximum/minimum values
• Frequent cycling of cooling fans as the ECM attempts to compensate for unreliable temperature data

Potential Causes

The most common technical failures causing E317 on used PC210LC-7 excavators include:

• Sensor connector corrosion at the hydraulic tank mounting point where moisture accumulates from ground-level exposure
• Harness chafing along the frame rail near the left-side track motor where the wiring bundle rubs against the chassis during operation
• Failed temperature sensor element (thermistor breakdown) due to age-related degradation in high-heat environments
• Broken wiring in the harness between the sensor and ECM, particularly at flex points near the swing bearing
• ECM connector terminal corrosion at pins 23-24 (sensor circuit connections) caused by humidity in older machines
• Ground circuit failure where the sensor ground shares a common point with other hydraulic sensors

How to Troubleshoot and Fix Code E317

Step 1: Visual Inspection and Connector Verification

Begin by locating the hydraulic oil temperature sensor on the left side of the hydraulic tank (near the suction strainer). Disconnect the two-pin connector and inspect for corrosion, bent pins, or oil contamination. On used excavators, this connector frequently shows green corrosion due to its low mounting position. Clean contacts with electrical contact cleaner and examine the harness for obvious damage or wear patterns.

Step 2: Sensor Resistance Testing

Using a digital multimeter (DMM), measure the resistance across the sensor terminals. At 20°C (68°F), the sensor should read approximately 2.2-2.8 kΩ. At operating temperature (80°C/176°F), resistance should drop to roughly 0.3-0.4 kΩ. Compare your readings against the values in the PC210LC-7 shop manual (Section 70-15-3). If readings are infinite (open circuit) or near zero (short circuit), replace the sensor with Komatsu part number 7861-93-3320 or equivalent.

Step 3: Wiring Harness Continuity Check

Disconnect the sensor and locate the ECM connector (behind the cab, right side panel). Using your DMM, check continuity between the sensor harness connector and ECM pins 23 (signal) and 24 (ground). Resistance should be less than 1.0 Ω for each wire. Pay special attention to the harness routing near the swing bearing and along the left track frame—these are known wear points on the PC210LC-7 where wiring insulation degrades over time.

Step 4: Voltage Supply Verification

With the ignition on but engine off, backprobe the sensor connector. Measure voltage between the signal wire (typically brown/white) and ground. You should see approximately 5.0V ± 0.2V reference voltage from the ECM. If voltage is absent, trace the harness for breaks or check the ECM power supply circuits. For used machines, verify all chassis ground points are clean and tight, as poor grounding commonly causes sensor circuit faults.

Step 5: Advanced Diagnostics with KOMTRAX or Diagnostic Software

Connect Komatsu diagnostic software (KOMTRAX Plus or equivalent dealer-level tool) to view live sensor data. Monitor the temperature reading while gently heating the sensor with a heat gun. The displayed temperature should increase smoothly without jumps or dropouts. Erratic readings during this test indicate intermittent wiring faults common in high-hour used excavators. Check harness flex points and zip-tie routing for proper support.

Critical Note for Used Excavator Owners: Before replacing the sensor, always inspect harness routing and support brackets. On machines with 5,000+ hours, vibration often loosens wire ties, allowing harnesses to contact moving components. Replace worn grommets and secure all wiring properly to prevent recurrence.

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Disclaimer: This guide provides general diagnostic procedures for the Komatsu PC210LC-7. Always consult the official service manual for your machine's specific serial number range and seek professional assistance from certified Komatsu technicians for complex electrical diagnostics or if you're unsure about any procedure.