Adblue error on Hitachi loader - Definitive solution
Introduction
AdBlue failure on the Hitachi ZW220 is a well-known problem which directly affects productivity on the worksite. This loader, equipped with a Cummins QSB 6.7 engine controlled by a CM2350 ECU, is sensitive to SCR (Selective Catalytic Reduction) system malfunctions. When an SCR fault occurs, the machine generally enters a degraded mode, with a progressive loss of power. In some cases, it may even come to a complete standstill, making it impossible to intervene without advanced diagnostics.
To avoid these costly interruptions, we offer the complete elimination of emission devices: AdBlue, FAP (particulate filter) and EGR (exhaust gas recirculation). This operation eliminates frequent sources of breakdown due to clogging, faulty sensors or poorly executed regeneration cycles. The engine's operating stability is restored, with no software limitations.
AdBlue fault diagnosis on Hitachi ZW220 - "SCR urea system is broken" message
During our intervention on a Hitachi ZW220 equipped with a Cummins QSB 6.7 engine and CM2350 ECU, the dashboard displayed the explicit message:
"The urea SCR system is broken", accompanied by warning icons linked to the gas aftertreatment system.
This message indicates a malfunction in the SCR (Selective Catalytic Reduction) system, responsible for injecting AdBlue into the exhaust line. When a critical fault is detected, the ECU triggers a power reduction strategy, followed by a progressive engine shutdown if the fault is not corrected.
-
These codes are taken from the Cummins Tier 4 guide for QSB 6.7 engines (valid for CM2350).
-
3238/SPN 4340 FMI 4 - Diesel Exhaust Fluid Line Heater 1 Circuit - Voltage Below Normal
Low voltage in AdBlue heater circuit.
👇 May cause "SCR urea broken" fault. -
3258/SPN 4340 FMI 5 - Diesel Exhaust Fluid Line Heater 1 State - Current Below Normal or Open Circuit
Open signal or low current, often due to broken heater or faulty wiring. -
3559/SPN ??? FMI ? - Diesel Exhaust Fluid Dosing Unit - Voltage Below Normal
Urea dosing unit energized, AdBlue injector inactive. -
3568/SPN 5394 FMI 7 - Diesel Exhaust Fluid Dosing Valve - Mechanical system not responding or out of adjustment
AdBlue valve mechanical fault or control failure. -
3714/SPN 1569 FMI 11/31 - Engine Protection Torque Derate
The engine switches to power reduction mode as soon as a critical SCR code is detected. -
5631/SPN 6928 FMI 31 - SCR System Cleaning Inhibited Due to System Timeout
SCR strategy suspended due to timeout, sign of persistent failure.
-
AdBlue fault reprogramming process on Hitachi ZW220
Reading the CM2350 ECU
The engine file is read out via Calterm (version 4 or 5), using a Cummins driver such as Inline 7 or Nexiq USB Link.
The operation can be carried out on the bench or directly via the diagnostic socket, depending on the active security in the CM2350 ECU.
The extracted file is in .bin or .caldepending on the method used (direct reading or via Workstation).
This file contains all engine parameters, including SCR, DPF, EGR management tables and fault logic.
Analysis of emission control units
Once the file is loaded into Calterm, several critical blocks are analyzed to identify the functions to be neutralized.
The aim is to precisely target the elements responsible for fault tripping and motor limitation strategies.
Blocks analyzed :
-
Aftertreatment Diagnostic Parameters: inducement triggers and delays
-
DEF Control Parameters: control of AdBlue pump and injector
-
DPF Sooth Load Estimation: filter regeneration estimation and thresholds
-
EGR Control Strategy: activation or deactivation of the EGR valve
-
Fault Management: DTC processing, thresholds and masking
Broadcast CAN frames are also checked, as some ECUs require certain values to remain present.
Even without physical sensors, data must remain logically consistent to avoid suppression detection.
Deleting and reprogramming
After analysis, the polluting functions are eliminated by a calibrated modification of the engine mapping.
We don't act on the surface: the complete logic is neutralized to prevent any future activation.
Changes made :
-
Deactivation of AdBlue injection and SCR cycles
-
Blocking DPF regeneration and soot calculations
-
Removal or inhibition of blocking faults (e.g. 3714, 3238, 3559)
-
Emulation of critical sensors with realistic constant values (NOx, temperature, pressure)
This reprogramming avoids classic reactions such as torque reduction, engine block timer or persistent codes.
Every action is controlled to ensure engine stability, even under high load conditions.
Checksum calculation and validation
Once the changes have been made, a recalculation of the checksums is essential to guarantee software validity.
Depending on the file structure, this recalculation can be carried out in Calterm or via an external third-party tool.
Each modified segment is checked line by line to avoid any risk of corruption.
A manual inspection is also carried out to prevent critical errors (invalid address, structural inconsistency, etc.).
ECU rewriting and field testing
The corrected file is injected into the CM2350 via Calterm, usually in calibration mode (no full flash required).
After restart, no faults should appear and engine power is immediately available.
Hot and under-load tests are carried out to validate stability, the absence of an inducement strategy and the consistency of CAN values.
The loader can then operate without AdBlue injection, DPF regeneration or electronic limitations.
Find out more about Hitachi and emissions deactivation
Visit our section dedicated to the Hitachi range to discover all our AdBlue, DPF and EGR suppression solutions, compatible with many models of loaders, excavators and other construction machinery.
👉 See all Hitachi products
Do you also work on Cummins engines (QSB, QSL, ISB, etc.) powering other machines?
Discover our page dedicated to specific interventions on Cummins engines, whatever the original manufacturer.
👉 See Cummins engine services
