RENAULT VOLVO trw ems2.4 adblue dosing limitation

About This Project

Renault / Volvo TRW EMS2.4 – AdBlue Dosing Limitation Calibration

The SCR systems based on the TRW EMS2.4 control unit are widely used in Renault and Volvo trucks. One of the most common issues these vehicles face is AdBlue dosing limitation, which leads to reduced engine power and increased fuel consumption. This happens when the ECU detects a fault in the SCR system and progressively restricts AdBlue injection — eventually triggering severe torque limitation.

Our Calibration Approach

Working with EMS2.4 requires a deep understanding of both fuel calibration and the internal SCR strategy. Our process is based on detailed analysis of CAL files and engineering DAMOS data, which reveal:

dosing coefficient maps;

torque limiters linked to SCR status;

configuration flags and logic conditions for AdBlue-related faults;

dependencies between catalyst thermal models and NH₃ storage calculations.

It’s important to note that SCR behavior in EMS2.4 cannot be disabled with a single switch — the dosing restriction is triggered by a multi-layered algorithm, so the solution must also be comprehensive.

What We Modify Inside the Software

During calibration, we perform several key procedures:

Disable the internal conditions that trigger dosing reduction.
This includes torque-reduction scenarios caused by low-quality reagent, low tank level, or pump driver faults.

Adjust AdBlue dosing limiter maps.
We do not deactivate the SCR system entirely; instead we remove unnecessary artificial restrictions applied by the ECU.

Neutralize “reverse timers” related to torque limitation.
EMS2.4 contains internal counters that maintain power limitation even after the fault is cleared. These are corrected as part of the calibration.

Preserve full diagnostic functionality.
The SCR system continues to operate normally, and the vehicle performs standard self-diagnostics — but without power loss or imposed limitations.

Results

After calibration:

all AdBlue dosing limitation issues are resolved;

engine power and drivability are restored;

the SCR system remains operational;

no hardware modifications or sensor bypassing are required.

We provide such calibrations for Renault Trucks, Volvo FE/FM/FH, and various machinery equipped with the EMS2.4 ECU.