What is XCMG B3.9-5.9-C8.3 CM2150 Fault Code 157-2?

Fault Code 157-2 indicates an "Injector Cylinder #2 - Data Erratic, Intermittent, or Incorrect" condition in the Cummins CM2150 electronic control system. This diagnostic trouble code (DTC) signals that the Engine Control Module (ECM) is receiving abnormal or inconsistent electrical data from the fuel injector circuit serving cylinder #2.

This fault specifically affects the closed-loop fuel delivery system, where the ECM continuously monitors injector performance to maintain precise combustion timing and fuel metering. In XCMG excavators equipped with Cummins B-series and C8.3 engines using CM2150 electronics, this code compromises fuel efficiency, power output, and emissions compliance. The intermittent nature of the "-2" suffix means the problem occurs sporadically, making diagnosis more challenging than constant failures.

Common Symptoms

• Rough idling or noticeable engine vibration, particularly when the machine is cold or under light load
• Intermittent power loss or hesitation during digging cycles, especially under heavy hydraulic demand
• Check Engine Light (CEL) illumination on the instrument cluster, potentially with amber warning status
• Increased exhaust smoke (white or gray) during acceleration or when the fault is actively occurring
• Fuel consumption increase of 10-15% due to improper fuel metering compensation by the ECM

Potential Causes

The most common root causes for Code 157-2 on used XCMG excavators include:

• Worn or damaged injector wiring harness at the cylinder #2 position, often caused by rubbing against valve covers or engine brackets over thousands of operating hours
• Corroded or loose electrical connectors at the injector plug, particularly in machines exposed to moisture or operating in humid environments
• Failing fuel injector solenoid in cylinder #2, where internal coil resistance falls outside specification (typically 0.3-0.9 ohms for CM2150 systems)
• Intermittent ECM ground connection issues, common in older machines where chassis ground points develop oxidation
• Injector harness chafing near the fuel filter housing or along the engine's right side—a known wear point on B-series Cummins installations

How to Troubleshoot and Fix Code 157-2

Step 1: Visual Harness Inspection
With the engine off, carefully inspect the injector wiring harness for cylinder #2. Look for abraded insulation, cracked wire jackets, or signs of contact with hot engine components. On used excavators, pay special attention to wire routing near vibration points and the valve cover edge.

Step 2: Connector and Resistance Testing
Disconnect the injector connector at cylinder #2. Using a digital multimeter, measure the resistance across the injector solenoid terminals—specification is typically 0.3-0.9 ohms. Also check connector pins for corrosion, bent terminals, or moisture intrusion. Clean contacts with electrical contact cleaner and dielectric grease.

Step 3: Perform Injector Swap Test
If resistance is within spec but the code persists, swap the cylinder #2 injector with cylinder #4. Clear codes using Cummins INSITE software or compatible diagnostic tool, then operate the machine. If Code 157-2 moves to cylinder #4, the injector is faulty. If it remains at #2, focus on harness or ECM issues.

Step 4: ECM Ground Verification
Check all ECM ground connections at the engine block and chassis. Resistance to true ground should be less than 0.1 ohms. Remove, clean with a wire brush, and re-torque ground studs to specification.

Disclaimer: This guide provides general troubleshooting procedures. Always consult the official Cummins service manual and consider professional diagnostic support for complex electrical issues, especially when ECM replacement may be necessary.