## What is Komatsu PC220-7 Fault Code E317?

**Komatsu PC220-7 fault code E317 indicates a malfunction in the hydraulic oil temperature sensor circuit.** This code is triggered when the Engine Control Module (ECM) detects an abnormal voltage signal from the hydraulic oil temperature sensor, typically reading either too high (open circuit) or too low (short circuit) compared to expected parameters.

The **hydraulic oil temperature sensor** monitors the working temperature of the hydraulic system fluid, which is critical for maintaining optimal viscosity and preventing component damage. On the PC220-7 excavator, this sensor communicates directly with the **ECM** to regulate pump output, protect system components, and prevent thermal overload. When E317 appears, the machine may enter a protective **derate mode** or display inaccurate temperature readings, compromising both performance and component longevity.

## Common Symptoms

- **Warning light** illuminated on the instrument panel (typically a yellow or amber caution indicator)
- **Inaccurate hydraulic oil temperature gauge** readings showing either maximum heat or minimum cold regardless of actual operating conditions
- **Reduced hydraulic power** or sluggish operation as the ECM enters protective mode
- **Error message** displayed on the monitor panel specifically referencing hydraulic temperature or sensor issues
- **Intermittent code appearance** during operation, especially on used machines with worn wiring harnesses

## Potential Causes

The most common causes of E317 on used PC220-7 excavators include:

- **Damaged or corroded wiring harness** between the hydraulic oil temperature sensor and ECM, particularly at known rub points near the hydraulic tank mounting area
- **Failed hydraulic oil temperature sensor** due to age, thermal cycling, or contamination from hydraulic fluid breakdown
- **Corroded or loose connector pins** at the sensor plug, especially common in machines exposed to moisture or extreme environments
- **Short circuit** in the sensor wiring caused by harness chafing against frame components or hydraulic lines
- **ECM internal fault** (less common) affecting the sensor input circuit
- **Voltage supply issues** from the machine's electrical system affecting sensor reference voltage

## How to Troubleshoot and Fix Code E317

**Step 1: Initial Visual Inspection**
Begin by locating the **hydraulic oil temperature sensor**, typically mounted on the hydraulic tank or main control valve assembly. Inspect the **wiring harness** from sensor to ECM for visible damage, abrasion, or evidence of contact with hot surfaces. On used excavators, pay special attention to **connector corrosion**—disconnect the sensor plug and examine pins for green oxidation or moisture intrusion.

**Step 2: Electrical Testing**
Using a **digital multimeter**, check sensor resistance. With the sensor disconnected and at ambient temperature (approximately 20°C/68°F), resistance should read between **2,000-3,000 ohms** (consult your service manual for exact specifications). Next, check for **continuity** in the wiring harness from sensor connector to ECM. Measure voltage at the sensor connector with ignition on—you should see approximately **5 volts reference voltage** from the ECM.

**Step 3: Component Testing and Replacement**
If wiring tests normal, test the sensor by warming it (in hot water, not open flame) while monitoring resistance—it should decrease predictably as temperature rises. A sensor showing **infinite resistance** (open circuit) or **zero resistance** (short circuit) requires replacement. Before installing new components on used machines, clean connector terminals with **electrical contact cleaner** and apply **dielectric grease** to prevent future corrosion.

**Step 4: Final Verification**
After repairs, clear the fault code using **Komatsu diagnostic software** or by disconnecting the battery for 5 minutes. Run the machine through a complete warm-up cycle and monitor the hydraulic temperature gauge for normal operation (typically 40-80°C during standard work). Re-check for codes after 30 minutes of operation.

**Disclaimer:** This guide provides general troubleshooting information. For used excavators with complex electrical issues or if you're uncertain about any procedure, consult a certified Komatsu technician or qualified heavy equipment mechanic. Always disconnect battery power before performing electrical repairs and follow manufacturer safety procedures.