What is Caterpillar Fault Code 1160-5?

Fault Code 1160-5 indicates an "Injector Cylinder #6 - Current Below Normal or Open Circuit" condition in Caterpillar electronic engines. This diagnostic trouble code (DTC) means the Electronic Control Module (ECM) has detected abnormally low electrical current or a complete circuit interruption in the fuel injector circuit for cylinder 6.

This code is critical because it directly affects fuel delivery to one cylinder, resulting in incomplete combustion, reduced power output, and increased emissions. The ECM continuously monitors injector current during operation, and when the circuit resistance exceeds acceptable parameters or the circuit opens completely, the system logs this fault to prevent engine damage and maintain emissions compliance.

Common Symptoms

• Engine misfiring or rough running, particularly noticeable at idle or under load
• Reduced power output and poor throttle response due to cylinder #6 not firing properly
• Check Engine Light or Malfunction Indicator Lamp (MIL) illuminated on the dashboard
• Increased fuel consumption and black or white smoke from the exhaust
• Engine derate mode may activate in severe cases, limiting maximum RPM and power to protect the engine

Potential Causes

The most common technical causes for Code 1160-5 on used Caterpillar excavators include:

• Failed fuel injector solenoid on cylinder #6 due to internal coil winding failure or mechanical wear
• Damaged wiring harness between the ECM and injector, especially at harness routing points where vibration causes wire chafing against engine components
• Corroded or loose electrical connectors at the injector or ECM, particularly common in machines exposed to moisture or extreme environments
• Open circuit in the injector harness due to broken wires inside the insulation jacket
• ECM internal driver circuit failure (less common but possible in high-hour machines)
• Poor ground connections affecting the injector circuit return path

How to Troubleshoot and Fix Code 1160-5

Step 1: Visual Inspection Begin by inspecting the injector wiring harness from the ECM to cylinder #6 injector. On used excavators, pay special attention to harness routing near engine mounts, valve covers, and sharp edges where wire insulation may have worn through. Check the injector connector for corrosion, moisture intrusion, or bent pins.

Step 2: Electrical Testing Using a digital multimeter, disconnect the cylinder #6 injector connector and measure injector coil resistance. Typical specification is 0.3-1.5 ohms (consult your specific engine service manual). An open circuit (infinite resistance) confirms injector failure. Next, check for continuity in the harness from the ECM connector to the injector connector with the harness disconnected at both ends.

Step 3: Advanced Diagnostics Connect Caterpillar Electronic Technician (Cat ET) diagnostic software to perform active injector tests. The software can command individual injectors and monitor actual versus commanded current. Compare cylinder #6 response to other cylinders. Check for voltage supply at the injector connector with the key on (should read battery voltage). For used machines, also inspect the ECM connector pins for corrosion or terminal backout, which can create intermittent connections.

Step 4: Repair and Verification Replace failed components—typically the injector, damaged harness sections, or corroded connectors. When installing a new injector, apply dielectric grease to connector terminals to prevent future corrosion. After repairs, clear codes using Cat ET and perform a test run under load to verify the fix.

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Disclaimer: This guide provides general troubleshooting information. Always consult your machine's service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs may cause further damage or safety hazards.