These engines are equipped with a common rail fuel system. The fuel injection pump and the fuel lines deliver fuel to an electronic unit injector in each cylinder. A solenoid on each injector meters the amount of fuel that is delivered by the injector. An Electronic Control Module (ECM) sends signals to two pressurizing assemblies on the pump and to the injector solenoids to control the injection of fuel.
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| Illustration 1 | g06113915 |
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Top view (1) Fuel rail (2) Diesel Oxidation Catalyst (DOC) (3) Diesel Particulate Filter (DPF) (4) Fuel Injector and trim code | |
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| Illustration 2 | g06093158 |
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Right side view (5) Electric starting motor (6) Timing window (7) Engine oil filter (8) Closed crankcase breather (9) Crankshaft pulley (10) Intake throttle valve (11) Oil fill (12) NRS valve (13) High-pressure fuel pump | |
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| Illustration 3 | g06093164 |
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Left side view (14) Port for block heater (15) NRS Cooler (16) Alternator (17) Flywheel housing | |
The electronic system consists of the ECM, the wiring harness, switches, sensors, and fuel injectors. The ECM consists of two main components, the control computer (hardware) and the flash file (software). The flash file contains the operational characteristics. The operating maps define the following characteristics of the engine:
- Horsepower
- Torque curves
- Engine speed (rpm)
Refer to Troubleshooting, Electronic Control System Circuit Diagram for additional information on the electronic control system.
The ECM interfaces with the machine via software and an electrical connector on the ECM. The ECM also communicates with machine systems via data links.
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| Illustration 4 | g06142042 |
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Power curve chart for C2.4 naturally aspirated engines in 305.5E2 Mini Hydraulic Excavators | |
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| Illustration 5 | g06142055 |
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Performance curve for C2.4 naturally aspirated engines in 304E2, 304.5E2, 305E2 Mini Hydraulic Excavators and 902C2, 903C2 Compact Wheel Loaders. | |
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| Illustration 6 | g06142060 |
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Performance curve for C2.4 turbocharged engines in 307E2 Mini Hydraulic Excavators. | |
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| Illustration 7 | g06093988 |
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Right front of engine Serial number location for C2.4 engines | |
This engine does not have the Caterpillar serial number format. The engine serial number will either have six or seven digit serial numbers. Refer to Special Instruction, REHS7930 for more information on the engine serial numbers format. There are several ways to determine the engine serial number.
- If the machine has the original engine, the original serial number can be found in SIMSi under "Product Configuration".
- Decal on top of the valve cover.
- The serial number can be found on the block, located under the fuel pump. Refer to Illustration 7.
Regeneration Levels of the Diesel
Particulate Filter (DPF)
Refer to System Operation, Aftertreatment System for operation of the passive and active regeneration system. Refer to the Operation and Maintenance Manual, Diesel Particulate Filter for the alert indicators and what actions, if any, are required of the operator.
The DPF regeneration levels are listed in Cat® Electronic Technician (Cat ET), and can be found under "DPF Performance" status screen, which is found under the "Information" drop down menu under "Status".
Mini Hydraulic Excavator Operator Interface
| Regeneration Description | Warning Category | DPF Indicator | Engine Indicator | Alert Indicator | Engine Derate | Required Operator Action | Running Time at Level |
| Regeneration Not Needed | None | None | None | None | No | None | N/A |
| Active Regeneration Requested | None | None | None | None | No | No Action Required | 30 minutes |
| Active Regeneration Required | None | X(1) | None | None | No | - Increase the engine speed. Refer to Operation and Maintenance Manual
Or - Allow a parked regeneration. Refer to Operation and Maintenance Manual |
2 to 3 hours(2) |
| Parked Regeneration Required | 2 | X(1) | X(3) | X(1) | Yes | - Allow a parked regeneration to occur. Refer to Operation and Maintenance Manual | 1 to 1.5 hours(2) |
| Manual Regeneration Required | 3 | X(1) | X(1) | X(4) | Yes, Alarm | - A regeneration must be completed through Cat (ET). If the engine is run through these warning indicators, the DPF will require servicing and may need replacing. Engine damage can also occur |
1 to 1.5 hours(2) |
| DPF Service Required | 3 | X(1) | X(1) | X(4) | Yes, Alarm | - A regeneration cannot be performed. - Remove, clean, and inspect the DPF. Refer to Special Instruction, REHS7788 After passing the inspection, or replacing the DPF, perform a DPF Soot Load Reset and then a Manual Regeneration through Cat (ET) |
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| (1) | Red |
| (2) | The "Running Time at Level" is the estimated engine operating time at that level before going to the next higher regeneration level. The times listed are approximate, and will vary based application, speed, and load |
| (3) | Amber |
| (4) | Flashing |
Compact Wheel Loader Operator Interface
| Regeneration Description | Warning Category | DPF Indicator | Engine Indicator | Alert Indicator | Engine Derate | Required Operator Action | Running Time at Level |
| Regeneration Not Needed | None | None | None | None | No | None | N/A |
| Active Regeneration Requested | None | None | None | None | No | No Action Required | 30 minutes |
| Active Regeneration Required | 1 | X(1) | None | None | No | - Increase the engine speed. Refer to Operation and Maintenance Manual Or - Allow a parked regeneration. Refer to Operation and Maintenance Manual |
2 to 3 hours(2) |
| Parked Regeneration Required | 2 | X(3) | X(3) | X(3) | Yes | - Allow a parked regeneration to occur. Refer to Operation and Maintenance Manual | 1 to 1.5 hours(2) |
| Manual Regeneration Required | 3 | X(1) | X(3) | X(4) | Yes, Alarm | - A regeneration must be completed through Cat (ET). If the engine is run through these warning Indicators, the DPF will require servicing and may need replacing. Engine damage can also occur |
1 to 1.5 hours(2) |
| DPF Service Required | 3 | X(1) | X(1) | X(4) | Yes, Alarm | - A regeneration cannot be performed. - Remove, clean, and inspect the DPF. Refer to Special Instruction, REHS7788 After passing the inspection, or replacing the DPF, perform a DPF Soot Load Reset and then a Manual Regeneration through Cat (ET) |
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| (1) | Amber |
| (2) | The"Running Time at Level" is the estimated engine operating time at that level before going to the next higher regeneration level. The times listed are approximate, and will vary based application, speed, and load |
| (3) | Red |
| (4) | Flashing |
The following diagnostic codes are created when the regeneration level is in the following modes: Parked Regeneration Required, Manual Regeneration Required, and DPF Service Required.
- 3701-15 (DPF Status: High - Least Severe): This code is present when the engine is in "Parked Regeneration Required"
- 3701-16 (DPF Status: High - Moderately Severe): This code is present when the engine is in "Manual Regeneration Required". At this level a Manual DPF regeneration is required.
- 3701-0 (DPF Status: High - Most Severe): This code is present when the engine is in "DPF Service Required". At this level a regeneration cannot be performed. The DPF must be removed, cleaned, and inspected. In addition, the DPF soot load reset must be performed with Cat ET.
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The soot load reset should only be performed after the DPF is cleaned or a new DPF is installed. If the Soot Load Reset is performed any other times, which can cause the DPF to crack or cause a fire. Higher levels of soot require slower, controlled active regenerations. If the Soot Load Reset is performed and the DPF is not clean or new, the ECM will assume that it is and the active regeneration will occur too quickly. |
The engine ECM determines when an active regeneration is required based on the following three parameters: Soot model determined by the ECM, Differential pressure measurement across the DPF, and Fuel burned.
These three parameters can be seen in ET under the DPF Performance – II status screen:
- Soot Model = DPF Soot Mass
- DPF Differential Pressure = DPF #1 Soot Mass #1
- Fuel Burned = DPF #1 Soot Mass #2
ET displays the soot load for each of these parameters in grams of soot. The Soot Model increases in increments of 4 g. The DPF Differential Pressure and Fuel Burned increase in increments of 1 g. When any of these parameters reach 21 g, the DPF Soot Load % will reach 100% and an active regeneration will be requested.
When the soot load reaches 100%, the regen level will change from "Regeneration Not Needed" to "Active Regeneration Requested". Refer to the previous table. The soot load will never increase above 100%. Instead the engine will progress through the different regeneration levels based on the time shown in the last column of the previous table.
The soot model not only increases in increments of 4 g, but it also starts out at 4 g. Since 21 g equal to 100% soot load, the lowest soot load will not be below 19% and frequently will start out in the mid to upper 20 percent.
Note: When doing a regeneration, the soot load may drop into the single digits right before it completes the regeneration. Then once it completes the soot load percentage will increase up to the mid to upper twenties
The DPF Differential pressure will trigger when the pressure is between 6.28 kPa (0.9 psi) and 10.3 kPa (1.5 psi). The Fuel Burned parameter will reach trigger when the ECM calculates approximately 250 L (66 gal) of fuel has been burned.
Active regeneration cannot be performed if there are active diagnostic codes, or active event codes. The codes must be resolved before an active regeneration can occur.
However, active regenerations can occur with the following active codes present:
- 3701-15 (DPF Status: High - Least Severe)
- 3701-16 (DPF Status: High - Moderately Severe)
- 523602-0 (High Frequency Regeneration)