Komatsu PC200-7 Fault Code E112: Complete Diagnostic Guide

What is Komatsu PC200-7 Fault Code E112?

Fault Code E112 on the Komatsu PC200-7 indicates a malfunction in the engine oil pressure sensor circuit or abnormally low engine oil pressure. This code is generated when the Engine Control Module (ECM) detects either a voltage signal outside the normal operating range from the oil pressure sensor, or actual oil pressure readings below the safe threshold for engine operation.

This fault is critical for the PC200-7's SAA6D102E-2 engine because insufficient oil pressure can lead to catastrophic engine damage within minutes. The ECM continuously monitors oil pressure to protect internal components like bearings, camshafts, and cylinder walls from friction damage. When E112 triggers, the system may activate protective measures to prevent engine destruction.

Common Symptoms

• Oil pressure warning lamp illuminated on the instrument panel (typically red)
• Engine derating or automatic shutdown after a brief warning period
• Audible alarm sounding from the operator's cab
• Visible low oil pressure reading on the digital monitor (below 50 kPa at idle or 300 kPa at rated RPM)
• Unusual mechanical noise from the engine, such as valve train ticking or knocking sounds indicating oil starvation

Potential Causes

Sensor and Electrical Issues:

• Failed or degraded oil pressure sensor (common failure point after 5,000+ hours)
• Damaged wiring harness between sensor and ECM, particularly where the harness passes near the engine block (known rub point on PC200-7 models)
• Corroded or loose connector pins at the sensor or ECM connection points

Mechanical Engine Problems:

• Genuinely low engine oil level due to leaks or consumption
• Worn oil pump (typical in machines exceeding 8,000 operating hours)
• Clogged oil filter or pickup screen restricting flow
• Excessive bearing clearances from normal wear in used excavators
• Wrong viscosity oil or degraded oil failing to maintain pressure

How to Troubleshoot and Fix Code E112

Step 1: Verify Actual Oil Condition Before diagnosing electrical faults, check the engine oil level on the dipstick with the machine on level ground. Inspect oil quality—contaminated or excessively thin oil can cause genuine pressure loss. On used excavators, internal leaks into the coolant system can dilute oil. Replace the oil filter and refill with Komatsu-specified 15W-40 diesel engine oil if needed.

Step 2: Test the Oil Pressure Sensor Locate the oil pressure sensor on the engine block (typically near the oil filter housing). Disconnect the electrical connector and inspect for corrosion, moisture, or bent pins—common issues in machines operating in wet conditions. Using a digital multimeter, measure resistance across the sensor terminals. The PC200-7 sensor should read approximately 150-180 ohms at room temperature. Compare against Komatsu specifications in the service manual. If readings are infinite or zero, replace the sensor.

Step 3: Verify Actual Oil Pressure Install a mechanical oil pressure gauge in place of the sensor to confirm actual pressure. Start the engine and check readings: idle pressure should be 50-100 kPa, and 300-450 kPa at 2,000 RPM. If mechanical gauge readings are normal but the code persists, the sensor or wiring is faulty. If pressure is genuinely low, investigate the oil pump, pressure relief valve, or internal engine wear.

Step 4: Inspect Wiring Harness Trace the sensor harness back to the ECM, checking for damaged insulation, especially where it contacts the engine block or frame. On used PC200-7 excavators, vibration causes harness chafing at mounting brackets. Check connector terminals for proper seating and clean any corrosion with electrical contact cleaner. Measure voltage supply from the ECM (should be 5V reference) and ground continuity.

Step 5: Clear Code and Monitor After repairs, use Komatsu diagnostic software (KOMTRAX or compatible scan tool) to clear the fault code. Operate the machine under load while monitoring oil pressure readings in real-time. If E112 returns immediately, recheck sensor installation and harness connections.

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Disclaimer: This guide provides general troubleshooting information for the Komatsu PC200-7 E112 fault code. Always consult the official Komatsu service manual for your specific machine serial number and software version. For used excavators with unknown maintenance history, professional diagnosis by a certified Komatsu technician is recommended to prevent misdiagnosis and costly engine damage.