What is Hyundai R335LC-9T Fault Code 157-2?

Fault Code 157-2 on the Hyundai R335LC-9T indicates an Injector Cylinder #2 Current Low abnormality, meaning the Electronic Control Unit (ECU) has detected insufficient electrical current flowing to the fuel injector on cylinder number two. This code is part of Hyundai's proprietary engine management diagnostics and signals a disruption in the fuel injection control circuit for that specific cylinder.

This fault is critical because the R335LC-9T's diesel engine relies on precise electronic fuel injection timing and delivery for optimal performance, fuel efficiency, and emissions compliance. When cylinder #2's injector receives inadequate current, combustion becomes incomplete or irregular, directly impacting power output and potentially causing long-term engine damage through carbon buildup or thermal stress on adjacent components.

Common Symptoms

When Code 157-2 is active, operators typically experience:

• Rough idle or noticeable engine vibration, especially at low RPM
• Loss of power during digging or lifting operations due to one cylinder misfiring
• Increased black or white exhaust smoke indicating incomplete combustion
• Check Engine Light (CEL) illuminated on the instrument cluster
• Potential engine derate mode where the ECU limits maximum RPM to protect the engine

Potential Causes

The most common technical reasons for this fault code include:

• Faulty fuel injector solenoid on cylinder #2 with increased internal resistance or open circuit
• Damaged injector wiring harness, particularly at rub points near the engine valve cover or where harnesses contact the frame
• Corroded or loose electrical connectors at the injector plug—extremely common in used excavators exposed to moisture and dirt
• ECU driver circuit failure where the control module itself cannot supply adequate current
• Poor ground connections on the engine block affecting injector circuit integrity
• Worn injector harness insulation from heat cycles and vibration over years of operation

How to Troubleshoot and Fix Code 157-2

Step 1: Visual Inspection Begin by inspecting the cylinder #2 injector connector for corrosion, moisture, or damaged pins. On used excavators, check the entire injector harness routing for obvious wear points, particularly where it contacts metal surfaces or experiences engine heat exposure.

Step 2: Electrical Testing Using a digital multimeter, disconnect the injector connector and measure resistance across the injector solenoid terminals. Typical resistance should be 0.3-0.8 ohms (consult service manual for exact specs). Check for continuity from the ECU connector to the injector—any reading above 1 ohm suggests wiring degradation.

Step 3: Power Supply Verification With the ignition on (engine off), measure voltage supply at the injector connector using a breakout harness. You should see battery voltage momentarily during cranking. If voltage is absent, trace back to the ECU and check associated fuses and relays.

Step 4: Connector Cleaning and Repair Clean all connectors with electrical contact cleaner and apply dielectric grease. For used machinery, replacing worn harness sections is often more cost-effective than chasing intermittent faults.

Step 5: Component Replacement If testing confirms injector failure, replace the cylinder #2 fuel injector with OEM or quality aftermarket parts. Always replace the injector seal and copper washer during installation to prevent combustion gas leaks.

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Disclaimer: This guide provides general diagnostic information. Always consult the Hyundai R335LC-9T service manual and consider professional diagnosis for complex electrical issues, especially on used equipment with unknown service history.