What is XCMG XE490D 3.3 CM2250 Fault Code 1674?

Fault Code 1674 indicates a Low Voltage Condition on the Engine Oil Pressure Sensor Circuit in the Cummins CM2250 engine used in XCMG XE490D excavators. This code triggers when the Engine Control Module (ECM) detects voltage readings below the specified threshold (typically below 0.5 volts) on the oil pressure sensor signal wire.

The oil pressure sensor is a critical component that monitors engine lubrication system performance in real-time. On the CM2250 engine platform, this sensor uses a variable resistance design that changes voltage output based on oil pressure. When the ECM receives abnormally low voltage signals, it cannot accurately determine if proper oil pressure exists, potentially putting the engine at risk. For used XCMG excavators, this code is particularly important because it may indicate aging electrical components or sensor degradation that could lead to catastrophic engine damage if ignored.

Common Symptoms

• Check Engine Light (CEL) illuminated on the instrument cluster with reduced engine power
• Engine derate mode activated, limiting RPM to 1500 or lower to protect components
• Oil pressure gauge reading erratically or showing zero pressure despite engine running normally
• Audible warning alarms sounding continuously during operation
• Difficulty starting or rough idle conditions in some cases

Potential Causes

The most common technical reasons for Code 1674 on used XCMG excavators include:

• Damaged or corroded sensor connector at the oil pressure sensor mounting location (common wear point on high-hour machines)
• Broken or chafed wiring harness between the sensor and ECM, especially where harness routes near engine vibration points or sharp edges
• Failed oil pressure sensor due to internal electrical fault or contamination from oil leaks
• Poor ground connection on the sensor circuit return path
• ECM internal fault on the sensor voltage supply circuit (rare, but possible on older units)
• Low engine oil level or pressure causing actual pressure drop that appears as electrical fault

How to Troubleshoot and Fix Code 1674

Step 1: Visual Inspection and Basic Checks Begin by checking actual engine oil level using the dipstick—low oil can cause genuine pressure issues. Inspect the oil pressure sensor (typically located on the engine block near the oil filter housing) for oil leaks, physical damage, or corroded connectors. On used excavators, pay special attention to connector pins for green corrosion or pushed-back terminals.

Step 2: Electrical Testing with Multimeter Disconnect the sensor connector and measure resistance across sensor terminals. A functioning sensor typically shows 50-350 ohms depending on temperature. Next, check supply voltage from the ECM—should read approximately 5 volts on the signal wire with ignition on, engine off. Measure continuity from sensor ground to battery negative; resistance should be less than 5 ohms.

Step 3: Harness and Wiring Verification Trace the sensor harness from sensor to ECM, looking for wire damage at common rub points: engine mount brackets, fuel line crossovers, and valve cover edges. For used machines, inspect where harnesses pass through bulkheads or tie-down points. Use a multimeter to perform a voltage drop test while wiggling the harness—any fluctuation indicates intermittent connection issues.

Step 4: Component Replacement and Verification If testing confirms sensor failure, replace with OEM or equivalent oil pressure sensor (Cummins part number specific to CM2250). After replacement, clear codes using Cummins INSITE diagnostic software or compatible scan tool. Run engine and monitor live data to confirm oil pressure readings match actual conditions (typically 10-15 PSI at idle, 30-60 PSI at operating RPM).

Disclaimer: This guide provides general troubleshooting information. Always consult the official XCMG service manual and qualified diesel technicians for definitive diagnosis and repair, especially on used equipment with unknown service history.