Sany Excavator Fault Code P135: Complete Diagnostic Guide

What is Sany Excavator Fault Code P135?

Fault Code P135 indicates a Fuel Injection Pump Speed Sensor Circuit Malfunction or abnormal signal from the engine speed sensor on Sany excavators. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects an inconsistent, missing, or out-of-range signal from the fuel pump speed sensor, which monitors the rotational speed of the injection pump to optimize fuel delivery and engine timing.

This code is critical because the fuel injection pump speed sensor provides real-time data that the ECM uses to regulate fuel quantity, injection timing, and overall engine performance. When this sensor circuit fails, the excavator's engine management system cannot accurately control combustion efficiency, leading to power loss, rough idling, and potential engine protection modes that limit machine productivity.

Common Symptoms

When Code P135 is active on your Sany excavator, you may experience:

• Check Engine Light (CEL) or malfunction indicator lamp illuminated on the instrument panel
• Engine derating or power limitation – machine enters limp mode with reduced hydraulic performance
• Rough or erratic idling with noticeable engine speed fluctuations
• Hard starting or extended cranking time, especially when the engine is cold
• Black smoke from exhaust due to improper fuel-air mixture from incorrect timing data

Potential Causes

Several technical issues can trigger P135 on used Sany excavators:

• Faulty fuel injection pump speed sensor – common failure point after 5,000+ operating hours
• Damaged or corroded wiring harness at sensor connector or along routing path near engine block
• Worn sensor mounting causing excessive vibration or air gap changes between sensor and reluctor wheel
• ECM internal fault or corrupted software calibration (less common)
• Poor electrical ground connections at engine harness grounding points
• Water intrusion or oil contamination in sensor connector from damaged seals

How to Troubleshoot and Fix Code P135

Step 1: Visual Inspection Locate the fuel injection pump speed sensor on the fuel pump housing. Inspect the sensor body, connector, and wiring harness for physical damage, oil contamination, corrosion, or chafing against engine components. On used excavators, check for harness wear at common rub points near motor mounts and fuel lines.

Step 2: Electrical Testing Using a digital multimeter (DMM), disconnect the sensor connector and measure resistance across the sensor terminals (typically 800-1200 ohms for inductive sensors – verify with Sany specifications). Check for continuity in the wiring harness from sensor to ECM connector. Inspect for short circuits to ground on both signal wires.

Step 3: Signal Verification With the engine running (if possible), use a Sany diagnostic software tool or compatible scan tool to monitor live sensor data. The speed sensor should show consistent RPM readings matching actual engine speed. Erratic signals or "0 RPM" readings indicate sensor or air gap issues.

Step 4: Component Replacement If testing confirms sensor failure, replace the fuel injection pump speed sensor with a genuine Sany or OEM-equivalent part. Clean the mounting surface, apply anti-seize compound to threads, and torque to specification (typically 8-12 Nm). Ensure the air gap between sensor tip and reluctor wheel is within 0.5-1.5mm. Clear fault codes with diagnostic software and perform a test run.

Professional Tip: On high-hour used machines, always inspect and clean all electrical connectors and ground points before replacing sensors, as corrosion frequently causes false codes.

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Disclaimer: This guide provides general diagnostic information for Sany excavator Code P135. Always consult your machine's service manual and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with high-pressure fuel system components.