Aftermarket June 2022

JUNE 2022 AFTERMARKET 27 and that the DPF pressure was within tolerance. However, it was not long before I figured something else was not quite right. Digging deeper The DPF pressure sensor reports the pressure-drop across the DPF to the engine computer. The pressure-drop across the DPF is used to calculate the soot load. I could see the DPF pressure sensor operating, however, the engine computer was not calculating soot loading, as this figure stayed at 0% after a 30-mile road test. Please refer to Fig.2. As the soot load is a direct calculation, performed via the engine computer, from the raw data provided by the differential pressure sensor, conformed to be proper, I was concerned about a software-related issue. Using a specialist piece of equipment, I read the engine computer’s software file and checked it against the original software file. I was concerned the ECU’s software had been manipulated to have the DPF and EGR valve deleted, and my suspicions were correct. Now I knew why the soot loading would not increase. Put simply, it was because it was no longer programmed to monitor for this fault. This type of tampering can only be done with intent. Therefore, someone was aware of the software on this vehicle. It is likely it had been tampered with, prior to heading to auction. However, without any previous history of the vehicle, it was difficult to determine that right away. Fig.3 Proper analysis leads to a proper repair By using this specialist piece of equipment, I could now flash program an original software file back onto the engine computer, restoring its ability to calculate soot loading, and carry out regeneration. A direct initial change can be seen, as the load level of the DPF was now reading 55%, after the programming was completed. Please refer to Fig.3. This was due to the engine computer using a base value. This changed once the vehicle had been driven and the pressure had been accounted for across the DPF. An extended road test confirmed the fix, as we could now see the soot loading of the DPF. It reacted in direct correlation with the DPF pressure, as we would expect, and no fault-codes were now present. To summarise, this vehicle had a DPF tampering solution applied to the engine computer, so the computer would not consider the pressures or faults related to the DPF system. However, the so-called solution, which was applied by the previous owner/repairer, was very poor and caused the engine light to be illuminated intermittently.