What is Komatsu PC210LC-8 Fault Code E-22?

Fault Code E-22 on the Komatsu PC210LC-8 excavator indicates a Main Relief Valve (MRV) solenoid circuit malfunction in the hydraulic system. This diagnostic trouble code is triggered when the Engine Control Module (ECM) detects an abnormal voltage or current condition in the electrical circuit controlling the main relief valve solenoid, which regulates maximum hydraulic system pressure.

The main relief valve is critical to the PC210LC-8's hydraulic performance, preventing system over-pressurization that could damage pumps, cylinders, and seals. When E-22 is active, the excavator's ECM may limit hydraulic function or reduce engine power to protect components. For used excavators, this code often points to age-related electrical degradation rather than mechanical valve failure, making proper diagnosis essential before expensive part replacement.

Common Symptoms

When fault code E-22 is present, operators typically experience:

• Hydraulic system derate with noticeably reduced digging force and boom/arm speed
• Warning indicator illuminated on the multi-function display panel
• Intermittent loss of hydraulic power, especially during high-demand operations
• Abnormal hydraulic response where attachment movements feel sluggish or inconsistent
• Engine may enter protection mode, limiting RPM to approximately 1,500-1,800 range

Potential Causes

The most common technical reasons for E-22 on used PC210LC-8 excavators include:

• Damaged or corroded wiring harness at the main relief valve solenoid connector (frequent vibration point)
• Failed MRV solenoid coil due to internal short circuit or open winding
• Chafed wiring along the main pump area where harnesses contact frame components during machine flex
• Corroded connector pins at the ECM or solenoid junction caused by moisture infiltration
• Faulty ECM output driver circuit (less common, but possible in high-hour machines)
• Intermittent ground connection issues at solenoid mounting bracket

How to Troubleshoot and Fix Code E-22

Step 1: Visual Inspection Begin by inspecting the main relief valve solenoid and its wiring harness near the main hydraulic pump. On used excavators, check for obvious wire damage, connector corrosion (white/green deposits), or harness routing that contacts moving components. Pay special attention to the flex point where harnesses exit the pump area—this is a known wear location on PC210LC-8 models.

Step 2: Electrical Testing Using a digital multimeter (DMM), disconnect the solenoid connector and measure coil resistance across the solenoid terminals. Typical specification is 8-12 ohms at room temperature. Next, check for voltage supply at the harness connector with ignition on—you should see approximately 12V. Test continuity from the solenoid ground pin to chassis ground (should read less than 1 ohm).

Step 3: Circuit and Component Verification Connect Komatsu diagnostic software (KOMTRAX or compatible) to monitor real-time solenoid command signals while operating controls. If the ECM commands activation but no current flow registers, replace the solenoid. If current flows but the valve doesn't respond, mechanical valve seizure may be present. For used machines, clean all connector terminals with electrical contact cleaner and apply dielectric grease before reassembly to prevent future corrosion.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific serial number and consider professional diagnostic assistance for complex electrical issues.