What is Hyundai R335LC-9T Fault Code 101-16?

Fault Code 101-16 on the Hyundai R335LC-9T excavator indicates a Data Valid But Below Normal Operating Range condition in the Engine Speed/Position Sensor circuit. This Failure Mode Indicator (FMI) 16 specifically means the Engine Control Module (ECM) is receiving a valid signal from the crankshaft position sensor, but the signal values are reading lower than the calibrated threshold for normal operation.

This code is critical because the crankshaft position sensor provides essential data to the ECM for fuel injection timing, engine speed calculation, and overall engine management. On Hyundai's Tier 4 Final R335LC-9T models equipped with HD34 engines, inaccurate crankshaft position data can trigger protective derate modes or prevent proper engine operation, directly impacting machine productivity and potentially causing costly downtime.

Common Symptoms

• Engine cranks but fails to start or experiences extended cranking times before firing
• Intermittent engine stalling during operation, particularly at idle or under load
• Check Engine light illuminated on the instrument cluster with reduced engine power
• Rough idle or irregular engine operation with inconsistent RPM readings on the monitor
• ECM triggering derate mode limiting engine power output to protect components

Potential Causes

In used excavators, particularly high-hour machines, this code typically stems from sensor degradation or wiring harness issues. The most common causes include:

• Failed or failing crankshaft position sensor due to heat exposure or internal component breakdown
• Damaged sensor wiring harness from rubbing against engine components near the flywheel housing (a known wear point on R335LC-9 models)
• Corroded or loose electrical connectors at the sensor or ECM due to moisture intrusion
• Excessive air gap between the sensor and reluctor wheel caused by mounting bracket wear or improper installation
• Low battery voltage or poor ground connections affecting sensor signal quality
• ECM calibration issues or internal ECM faults (less common)

How to Troubleshoot and Fix Code 101-16

Step 1: Visual Inspection Begin with a thorough inspection of the crankshaft position sensor located on the lower left side of the engine near the flywheel housing. Check for physical damage, oil contamination, or mounting looseness. On used excavators, carefully inspect the sensor wiring harness from the sensor to the ECM connector, looking for chafing points where the harness contacts the engine block or frame rails—a common failure point after 5,000+ operating hours.

Step 2: Electrical Testing Using a digital multimeter, check the sensor resistance. The crankshaft position sensor should typically read between 200-1,000 ohms (verify exact specification in Hyundai service manual). Disconnect the sensor connector and measure resistance across the sensor terminals. Also perform a voltage drop test on the sensor harness while wiggling wires to identify intermittent open circuits.

Step 3: Air Gap Verification Measure the air gap between the sensor tip and the reluctor wheel teeth using a feeler gauge. The specification is typically 0.5-1.5mm (0.020-0.060 inches). Excessive gap indicates worn mounting hardware or incorrect sensor installation—common in used machines that have undergone previous repairs.

Step 4: Signal Testing with Diagnostic Software Connect Hyundai Hi-MATE or compatible diagnostic software to monitor real-time sensor data. Crank the engine and observe the RPM signal quality. Erratic readings or dropout patterns confirm sensor or wiring faults. For used excavators, simultaneously check battery voltage (should maintain above 11.5V during cranking) as weak batteries can cause false low-signal codes.

Step 5: Component Replacement If testing confirms sensor failure, replace with a genuine Hyundai crankshaft position sensor (Part# 39310-84500 or equivalent). When installing, clean the mounting surface thoroughly, apply a thin coat of anti-seize to threads, and torque to 10-12 Nm. Before reinstalling harness connectors, clean terminals with electrical contact cleaner and apply dielectric grease to prevent future corrosion.

---

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hyundai service manual for your specific machine serial number and seek assistance from certified Hyundai technicians for complex repairs, especially those involving ECM programming or warranty-related issues.