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Anti-pollution fault on Sany SY500 - SCR problem on Cummins engine

QSG 12

Anti-pollution fault on Sany SY500 - How to solve it permanently?

Introduction

The Sany SY500, equipped with the Cummins QSG12 engine, frequently suffers SCR-related breakdowns. An emission control fault on the Sany SY500 can lead to loss of power, unscheduled stops and high maintenance costs. To avoid these problems, devices such as AdBlue or DPF, which are often responsible for these failures, are removed. By reprogramming the CM2350 ECU, these functions are deactivated without affecting engine performance. As a result, the machine runs faultlessly, without clamping, and without unnecessary maintenance.

Fault diagnosis for Anti-pollution fault on Sany SY500 (ECU CM2350)

A complete and precise diagnosis is essential before any work is carried out on the emission control system of a machine like the Sany SY500 equipped with the CM2350 engine. Indeed, it is not uncommon for certain recurring errors to persist despite the replacement of several components. This situation often leads operators to consider removing the faulty system once and for all, to avoid costly and repeated downtime.

During our work on this model, several faults were identified, each requiring special attention to understand their origin and implications:

Anti-pollution fault on Sany SY500 - List of codes encountered
Anti-pollution fault on Sany SY500 - List of codes encountered
Code 3596 - Aftertreatment 1 Diesel Exhaust Fluid Pressure - Data Erratic, Intermittent, or Incorrect
Traduction : Pression du fluide AdBlue - Données erratiques, intermittentes ou incorrectes

Code 3596 ACTIVE PRESENT 17 TIMES
This code indicates a problem with the consistency of the DEF / AdBlue pressure reading. The ECU receives erratic, intermittent or incorrect data, suggesting a malfunction in the pressure sensor or a fault in the circuit (clogging, leak, clogged dispenser). The probability of failure is high. This type of fault can deactivate the SCR (Selective Catalytic Reduction) system, rapidly leading to an engine-limiting strategy with progressive loss of power.


Code 3574 - Aftertreatment 1 Diesel Exhaust Fluid Pressure - Data Valid But Below Normal Operating Range - Moderately Severe Level
Traduction : Pression du fluide AdBlue - Données valides mais en dessous de la plage normale (niveau modérément sévère)

Code 3574 CURRENTLY INACTIVE BUT RETURNS AFTER 30MIN
This fault indicates that the DEF fluid pressure is detected but is outside the normal operating range, at too low a level. This may be due to insufficient flow, partial clogging, or a faulty dispenser. Although the signal remains technically valid, this type of anomaly is closely monitored by the system, and may, if it persists, trigger an inducement strategy. The probability of failure is moderate, but the consequences can quickly become critical if no corrective action is taken.


Code 3712 - Aftertreatment SCR Operator Inducement - Data Valid But Above Normal Operating Range - Most Severe Level
Translation: SCR Inducement - Data Valid But Above Normal Operating Range (Most Severe Level)

Code 3712 CURRENTLY INACTIVE BUT RETURNS AFTER 30MIN
This code corresponds to a critical threshold in SCR system management. It confirms the activation of an engine cut-out strategy, triggered when the permissible exhaust gas treatment tolerances are exceeded. In practice, this means an immediate reduction in available power to force an intervention. This is a serious fault. It often follows on from other untreated codes (DEF pressure, SCR sensors, metering unit), and can even block restarts if ignored.


Faults below are recurrent, appearing more than 60 times and recurring after 15 to 30 minutes:


Code 4947 - Aftertreatment 1 Diesel Exhaust Fluid Doser Heating Mode Request - Condition Exists
Translation: AdBlue Doser Heating Mode Request - Condition active

Code 4947 CURRENTLY INACTIVE BUT RETURNS AFTER 30MIN
This code indicates that the system has requested activation of the AdBlue dispenser heating mode. This function is essential in low-temperature conditions, to prevent freezing or crystallization of the fluid. If heating is not activated correctly, DEF injection is suspended, thus disabling SCR treatment. This fault, often linked to a faulty thermal sensor or resistor, has a moderate probability of occurrence, but can lead to a severe inducement strategy if the situation persists.


Code 1682 - Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit Input Lines - Condition Exists
Translation: AdBlue dosing unit input lines - Condition active

Code 1682 CURRENTLY INACTIVE BUT RETURNS AFTER 30MIN
This fault concerns the DEF dispenser input lines, including the integrated temperature, pressure and flow sensors. When a malfunction is detected on these signals, the ECU considers the system unreliable, resulting in immediate cut-off of AdBlue injection. This is a common fault, with a high probability of failure, particularly in the case of a faulty dispenser or damaged connector. This code is a direct trigger for engine inductance, with reduced torque and power.


Code 3714 - Engine Protection Torque Derate - Condition Exists
Translation: Engine Torque Derate by Protection Strategy - Active Condition

Code 3714 CURRENTLY INACTIVE BUT RETURNS AFTER 30MIN
This code indicates that the engine has undergone a torque reduction applied as a protection strategy. It does not represent an isolated fault, but a direct consequence of one or more faults in the emission control system. The ECU has set up this clamping to protect the engine or force a repair. Even if the code is currently inactive, it attests to the fact that a period of engine limitation has recently occurred, which may justify the performance losses observed by the user.

Anti-pollution fault on Sany SY500 - Programming steps
Anti-pollution fault on Sany SY500 - Programming steps

Reprogramming steps after an emission fault on Sany SY500 Definitive deletion

When an anti-pollution fault occurs on a Sany SY500, the machine often enters degraded mode, with loss of power and error messages on the dashboard. To restore normal operation without costly component replacement, the problem can be permanently corrected by targeted reprogramming of the engine ECU. Here's how it's done, step by step.

Step 1: Diagnosis and ECU reading

The first step is a complete engine system diagnosis. Using a specialized tool, any faults present are identified, then the ECU data is retrieved. This extracts a file containing all the engine's current configuration. This step is essential, as it enables precise, targeted intervention.

Step 2: File analysis and preparation for modification

Once the file has been retrieved, it is analyzed in detail to pinpoint the zones linked to the SCR, DPF or EGR systems. The aim is simple: deactivate only the problem areas, without affecting the engine's essential functions. In this way, the modification remains clean, efficient and totally reversible if necessary.

Step 3: Remove restrictions and clamping strategies

At this stage, the elements responsible for power limitations are neutralized. In addition, the automatic strategies that reduce engine torque as soon as an emission fault is detected are eliminated. Thanks to these adjustments, the engine runs smoothly and consistently, with no loss of performance on the Sany SY500.

Step 4: Checking the modified file

Before rewriting, it's essential to check that the file is completely consistent. This ensures that all data is stable and error-free, and that the ECU will accept the new configuration without risk. As a result, this step ensures the reliability of the intervention.

Step 5: Rewriting and validation in the field and definitive elimination of the anti-pollution fault on Sany SY500

Once the file has been validated, it is fed back into the ECU via the programming tool. The machine is then tested under real-life conditions. This ensures correct starting, total absence of faults, and full return of engine performance. This is why reprogramming the Sany SY500 permanently eliminates the anti-pollution fault, without having to replace any parts.

More about Sany and emission deactivation

Do you work on other Sany models? Discover all our AdBlue, DPF and EGR suppression solutions in the section dedicated to the Sany range.

Do you also work on different Cummins engines? Visit our page dedicated to Cummins engines to find out more about our compatible services.

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