What is Komatsu PC110-7 Fault Code E-22?

Fault Code E-22 on the Komatsu PC110-7 excavator indicates a hydraulic oil temperature sensor circuit malfunction or abnormally high hydraulic oil temperature exceeding manufacturer specifications. This code is triggered when the machine's Electronic Control Module (ECM) detects either a sensor voltage outside the normal operating range (typically 0.5-4.5V) or when hydraulic fluid temperatures exceed 95°C (203°F).

This diagnostic trouble code is critical for the PC110-7 because excessive hydraulic temperatures directly impact seal integrity, fluid viscosity, and component longevity. The hydraulic system operates multiple functions simultaneously—boom, arm, bucket, and swing operations—making temperature regulation essential for preventing catastrophic pump failure or seal degradation in this compact excavator model.

Common Symptoms

When Code E-22 is active on your Komatsu PC110-7, you may experience:

• Warning light illuminated on the instrument panel, often accompanied by an audible alarm
• Sluggish hydraulic response or reduced implement speed, particularly during extended operation
• Automatic derate mode activation, limiting engine RPM to protect hydraulic components
• Visible steam or strong odor from hydraulic tank breather cap
• Intermittent code storage that appears during high-load operations or warm ambient conditions

Potential Causes

The most common technical causes for E-22 on used PC110-7 excavators include:

• Hydraulic oil temperature sensor failure due to internal resistance drift (common after 5,000+ hours)
• Damaged or corroded wiring harness near the hydraulic tank, especially where the harness contacts the frame rail
• Clogged or restricted hydraulic oil cooler fins packed with debris, reducing heat dissipation efficiency
• Low hydraulic fluid level causing inadequate cooling circulation and localized hot spots
• Faulty ECM ground connections at G102 (frame ground point) creating voltage reading errors
• Actual hydraulic overheating from worn main pump components generating excessive heat

How to Troubleshoot and Fix Code E-22

Step 1: Visual Inspection and Fluid Check Begin by inspecting hydraulic oil level through the sight glass with the machine on level ground. Check for proper oil grade (Komatsu recommends ISO VG46 hydraulic fluid). Examine the hydraulic cooler for blockages—on used excavators, this is frequently packed with dirt and construction debris.

Step 2: Sensor Circuit Testing Locate the hydraulic temperature sensor on the left side of the hydraulic tank. Disconnect the two-pin connector and measure resistance across sensor terminals using a digital multimeter. At 20°C (68°F), resistance should read approximately 2.4-2.6 kΩ. Compare readings against Komatsu's temperature-resistance chart. Inspect connector pins for corrosion—a common issue on machines operating in wet environments.

Step 3: Wiring Harness Inspection Trace the sensor harness from tank to ECM, paying special attention to routing near the swing bearing and along the left track frame. On used PC110-7 models, this harness commonly rubs against frame edges, causing intermittent shorts. Check for voltage at the ECM connector (Pin 32)—should read approximately 5V reference voltage with sensor disconnected.

Step 4: Advanced Diagnostics If sensor and wiring test properly, connect Komatsu diagnostic software (KOMTRAX) to monitor real-time hydraulic temperature versus sensor output. This identifies ECM calculation errors versus actual overheating conditions. For used excavators, perform a thermal imaging scan of hydraulic components to locate abnormal heat sources indicating pump wear or valve leakage.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu PC110-7 service manual and consider professional diagnosis for complex electrical issues or if unfamiliar with high-voltage systems.