Komatsu PC400LC-6 Fault Code E316: Complete Diagnostic Guide

What is Komatsu PC400LC-6 Fault Code E316?

Fault Code E316 indicates a malfunction in the engine oil pressure sensor circuit or abnormally low engine oil pressure detected by the Electronic Control Module (ECM). This code specifically relates to the oil pressure monitoring system that protects the Komatsu SAA6D125E-3 engine from catastrophic damage due to inadequate lubrication.

The oil pressure sensor sends continuous voltage signals to the ECM, which monitors whether oil pressure remains within safe operating parameters. When the sensor circuit shows an open/short condition or actual pressure drops below threshold values (typically below 50 kPa at idle), the ECM triggers E316. This is critical because insufficient oil pressure can lead to bearing failure, piston seizure, and complete engine destruction within minutes of operation.

Common Symptoms

When Code E316 is active, operators typically experience:

• Engine warning light illuminated on the instrument cluster, often accompanied by an audible alarm
• Automatic engine derate or shutdown in severe cases, limiting RPM to protect internal components
• Erratic oil pressure gauge readings or gauge showing zero pressure despite engine running normally
• Intermittent code activation during cold starts or when operating on steep slopes
• Loss of power as the ECM enters protective mode to prevent engine damage

Potential Causes

The most common technical causes for E316 on used PC400LC-6 excavators include:

• Failed oil pressure sensor (Komatsu part #6732-81-3140) due to internal diaphragm deterioration or contamination
• Damaged wiring harness between the sensor and ECM, particularly at known rub points near the engine mount brackets
• Corroded or loose connector pins at the sensor plug (3-pin connector), common in machines with 8,000+ operating hours
• Actual low oil pressure caused by worn oil pump, clogged oil filter, or bearing clearance issues
• ECM internal fault in the sensor input circuit (rare but possible in high-hour machines)
• Low engine oil level or use of incorrect viscosity oil affecting pressure readings

How to Troubleshoot and Fix Code E316

Step 1: Visual Inspection and Basic Checks Begin by checking actual engine oil level using the dipstick—low oil is the simplest cause. Inspect the oil pressure sensor (located on the left side of the engine block near the oil filter housing) for physical damage, oil leaks, or loose mounting. Examine the wiring harness from sensor to ECM for chafing, cuts, or heat damage, paying special attention to areas where the harness contacts the engine block or frame.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor connector and measure resistance across the sensor terminals. A functional sensor typically shows 50-150 ohms at room temperature (consult Komatsu service manual for exact specifications). Check for supply voltage at the connector (should be approximately 5V from ECM). Test harness continuity from sensor connector to ECM pins, and verify no shorts to ground (resistance should be >10kΩ to chassis ground).

Step 3: Mechanical Pressure Verification Install a mechanical oil pressure gauge in place of the sensor to verify actual oil pressure. At normal operating temperature, pressure should read 300-450 kPa at rated RPM. If mechanical pressure is adequate but the code persists, replace the oil pressure sensor. For used excavators, always apply dielectric grease to connector pins during reassembly to prevent future corrosion.

Step 4: Advanced Diagnostics If the sensor and wiring test correctly but low pressure is confirmed, investigate the oil pump (check for wear or internal bypass valve failure), inspect the oil filter for restrictions, and consider performing an oil analysis to check for bearing material indicating internal wear. Use Komatsu KOMTRAX or compatible diagnostic software to monitor real-time sensor values and verify ECM functionality.

Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific machine serial number. If you lack proper diagnostic tools or experience with high-pressure hydraulic systems, consult a certified Komatsu technician to prevent injury or further equipment damage.