What is Komatsu PC160LC-7 Fault Code E317?

Fault Code E317 on the Komatsu PC160LC-7 indicates a malfunction in the engine speed sensor circuit, specifically an intermittent or inconsistent signal being received by the Engine Control Module (ECM). This code means the ECM is detecting irregular voltage patterns or signal dropouts from the engine speed sensor (also called the crankshaft position sensor), which is critical for proper fuel injection timing and engine management.

The engine speed sensor on this Komatsu model plays a vital role in monitoring crankshaft rotation speed and position. The ECM relies on this data to calculate precise fuel delivery, control injection timing, and manage overall engine performance. When signal integrity is compromised, the machine's computer cannot accurately regulate combustion cycles, potentially leading to reduced power output, rough operation, or complete shutdown to protect internal components.

Common Symptoms

When Code E317 is active on your PC160LC-7, operators typically experience:

• Intermittent engine stalling or unexpected shutdown, especially during idle or low-load operation
• Engine warning light illuminated on the dashboard, possibly accompanied by audible alarms
• Rough idle or inconsistent engine RPM, with noticeable fluctuations during operation
• Loss of power or hesitation during hydraulic work cycles, particularly under heavy loads
• Difficulty restarting the engine after it has warmed up or following a shutdown event

Potential Causes

The most common technical reasons for E317 appearing on used PC160LC-7 excavators include:

• Worn or damaged engine speed sensor, particularly common on machines with over 5,000 operating hours
• Corroded or loose electrical connectors at the sensor itself or at ECM connection points
• Harness chafing or wire damage where the sensor cable runs near the engine block or along the frame rails (known wear point on this model)
• Oil or debris contamination on the sensor pickup face, interfering with magnetic signal generation
• ECM internal fault (less common), where the signal processing circuit has degraded
• Improper sensor air gap due to incorrect installation during previous repairs

How to Troubleshoot and Fix Code E317

Step 1: Visual Inspection Begin by locating the engine speed sensor on the flywheel housing (driver's side of the engine block). Inspect the sensor mounting, checking for physical damage, excessive oil buildup, or incorrect positioning. Verify the air gap between the sensor tip and flywheel teeth is within Komatsu specification (typically 0.5-1.5mm). Clean any contamination from the sensor face using brake cleaner.

Step 2: Electrical Connection Check Disconnect the sensor harness connector and thoroughly inspect both male and female terminals for corrosion, bent pins, or moisture intrusion. On used excavators, this connection point frequently develops green corrosion due to environmental exposure. Clean contacts with electrical contact cleaner and apply dielectric grease. Trace the wiring harness back to the ECM, checking for obvious abrasion points where the cable contacts frame members or heat shields—a common failure point on older PC160LC-7 machines.

Step 3: Resistance and Voltage Testing Using a digital multimeter, measure sensor resistance across the two sensor terminals. The specification should be approximately 190-250 ohms at room temperature (consult your service manual for exact values). Test harness continuity from sensor connector to ECM pins, ensuring readings below 1 ohm. Check for shorts to ground on both circuits. If readings are out of specification, replace the sensor or repair damaged harness sections.

Step 4: Dynamic Signal Test Reconnect the sensor and use Komatsu diagnostic software (KOMTRAX or compatible scan tool) to monitor live sensor data while cranking the engine. The signal should show consistent AC voltage pulses (typically 0.5-5V amplitude) as the flywheel rotates. Erratic signals or dropouts confirm sensor failure. For used machines, consider replacing the sensor preventatively if readings are borderline, as intermittent failures will continue causing downtime.

Step 5: Final Verification After repairs, clear the fault code using diagnostic software, operate the machine through a complete work cycle, and verify no code reappearance. Monitor engine RPM stability on the display during idle and loaded conditions.

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Disclaimer: This guide provides general troubleshooting information for the Komatsu PC160LC-7. Always consult the official Komatsu service manual for your specific machine serial number and engine configuration. If you lack proper diagnostic tools or experience with heavy equipment electronics, consult a certified Komatsu technician to avoid incorrect diagnosis or further damage to electrical systems.