What is Caterpillar Fault Code SPN2373?

SPN 2373 indicates a problem with the Diesel Particulate Filter (DPF) Intake Pressure Sensor circuit, specifically detecting an abnormal voltage condition or sensor malfunction. This Suspect Parameter Number monitors the pressure differential across the diesel particulate filter, which is critical for the aftertreatment system's regeneration process and overall emissions control.

This fault code is particularly important for Caterpillar excavators equipped with Tier 4 Final or Stage IV emissions systems. The DPF intake pressure sensor provides essential data to the Engine Control Module (ECM) to determine when active or passive regeneration is required. When SPN 2373 triggers, the ECM cannot accurately assess filter loading, potentially leading to incomplete regenerations, excessive soot accumulation, or unnecessary engine derating. For used excavators, this code often appears after extended operating hours when sensors degrade or wiring harnesses experience environmental damage.

Common Symptoms

• Check Engine Light (CEL) or Diesel Exhaust Fluid (DEF) warning lamp illuminated on the instrument cluster
• Engine power derate or reduced performance, particularly during high-load operations
• Frequent or unsuccessful regeneration cycles, causing excessive fuel consumption
• ECM diagnostic codes stored in memory, potentially accompanied by SPN 3251 or SPN 3246 (related aftertreatment faults)
• Abnormal exhaust system behavior, including excessive heat or unusual regeneration frequency

Potential Causes

The most common technical reasons for SPN 2373 on used Caterpillar excavators include:

• Faulty DPF intake pressure sensor due to carbon buildup, heat exposure, or internal sensor element failure
• Damaged wiring harness or connector corrosion at the sensor connection point, especially near exhaust components where heat cycling occurs
• Open or short circuit in the sensor signal wire between the sensor and ECM
• ECM voltage supply issues providing incorrect reference voltage (typically 5V) to the sensor
• Clogged or damaged pressure sensing tubes leading to the sensor, causing false readings
• Previous repair attempts with incorrect sensor calibration or aftermarket sensor incompatibility

How to Troubleshoot and Fix Code SPN2373

Step 1: Visual Inspection and Connection Check Begin by locating the DPF intake pressure sensor on the aftertreatment system inlet. Inspect the wiring harness for obvious damage, melting, or chafing against exhaust components—a common issue in used machines. Disconnect the sensor connector and examine pins for corrosion, bent terminals, or moisture intrusion. Clean connections with electrical contact cleaner if contamination is present.

Step 2: Electrical Testing with Diagnostic Tools Using a digital multimeter, check the reference voltage from the ECM at the sensor connector (key on, engine off). You should measure approximately 5 volts on the reference pin. Next, measure sensor output voltage with the engine running—typical readings range from 0.5V to 4.5V depending on DPF loading. Consult Caterpillar Electronic Technician (Cat ET) software for specific voltage parameters for your machine model.

Step 3: Sensor and Circuit Verification If voltage readings are out of specification, perform a resistance check on the sensor itself (typically 1,000-3,000 ohms at room temperature). Check wiring continuity from sensor to ECM connector, and test for shorts to ground. For used excavators, pay special attention to harness routing near hot exhaust components where insulation breakdown commonly occurs. Replace the sensor if internal resistance is abnormal, or repair/replace harness sections showing damage.

Step 4: Clear Codes and Verify Repair After repairs, clear fault codes using Cat ET and perform a regeneration cycle to verify proper sensor operation under load conditions.

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Disclaimer: This guide provides general diagnostic information. Always consult your Caterpillar service manual and consider professional diagnostic services for complex electrical or emissions system issues, especially on used equipment with unknown service history.