Sany SY215CA Fault Code P1572(81): Complete Diagnostic Guide

What is Sany SY215CA Fault Code P1572(81)?

Fault Code P1572(81) indicates a malfunction in the Engine Speed Sensor Circuit or crankshaft position sensor signal abnormality. This code triggers when the Electronic Control Module (ECM) detects an irregular, missing, or intermittent signal from the engine speed sensor, which is critical for monitoring crankshaft rotation and timing.

On the Sany SY215CA excavator, this sensor provides real-time data to the ECM for fuel injection timing, engine speed control, and diagnostic monitoring. When this circuit fails, the machine cannot accurately determine engine position or RPM, leading to significant performance degradation. This is especially critical in used excavators where sensor degradation and wiring harness wear are common failure points.

Common Symptoms

When P1572(81) is active on your SY215CA, you may experience:

• Hard starting or extended cranking before the engine fires
• Engine running rough at idle or experiencing irregular RPM fluctuations
• Check Engine Light (CEL) or malfunction indicator illuminated on the dash
• Engine derate mode activating, limiting power output and hydraulic performance
• Sudden engine stalling during operation, particularly under load or at idle

Potential Causes

The most common technical reasons for P1572(81) on used Sany excavators include:

• Worn or failed crankshaft position sensor due to heat exposure and vibration over time
• Damaged sensor wiring harness from rubbing against engine components or frame rails (common wear point near the flywheel housing)
• Corroded or loose electrical connectors at the sensor or ECM interface
• Damaged reluctor ring (tone wheel) on the crankshaft or flywheel
• ECM internal fault or corrupted sensor calibration data
• Water intrusion into sensor connector from seal deterioration in older machines

How to Troubleshoot and Fix Code P1572(81)

Step 1: Visual Inspection Begin by locating the engine speed sensor (typically mounted near the flywheel housing or crankshaft pulley). Inspect the sensor body for physical damage, oil contamination, or excessive gap from the reluctor ring. Check the wiring harness for chafing, cuts, or evidence of rodent damage—a frequent issue in stored used equipment.

Step 2: Electrical Testing Using a digital multimeter, test the sensor's resistance (typically 200-1000 ohms depending on sensor type—consult Sany specifications). Measure voltage output while cranking the engine; you should see an AC voltage signal. Inspect all connector pins for corrosion, bent terminals, or moisture. Clean connectors with electrical contact cleaner and apply dielectric grease.

Step 3: Advanced Diagnostics Connect Sany diagnostic software or a compatible scan tool to monitor live sensor data. Check for intermittent signal dropout during engine cranking. Inspect the reluctor ring through the sensor opening for missing teeth, cracks, or metallic debris buildup. For used excavators, verify the air gap between sensor and reluctor ring (typically 0.5-1.5mm).

Step 4: Component Replacement If testing confirms sensor failure, replace with an OEM or quality aftermarket crankshaft position sensor. When replacing on used machinery, always replace the connector pigtail if corrosion is present. Clear codes with diagnostic software and perform a relearn procedure if required by the ECM.

---

Disclaimer: This guide provides general troubleshooting procedures. Always consult the official Sany service manual for your specific machine serial number and consult a certified heavy equipment technician for complex electrical diagnostics or ECM programming issues.