I was booked to clean a blocked Transit DPF in Stockton-on-Tees because the customer was told the DPF was blocked by another garage & required cleaning.

Diagnosis

I always start with a fault code scan and I have to bear in mind some fault codes may not be present as they have often been deleted beforehand which isn’t a good idea if you don’t understand what has caused them.

I was presented with the following codes:

P2033 – Exhaust Gas Temperature Sensor Circuit High Bank 1 Sensor 2
P246C – Particulate Filter Restriction – Forced Limited Power (Bank 1)
P2463 – Particulate Filter Restriction – Soot Accumulation (Bank 1)

I then view actual live data to establish the calculated soot level, and also measure the exhaust differential pressure so I can decide if the DPF does require cleaning, in this case it could be cleared with a regeneration, the temperature sensor fault is however preventing a regeneration taking place, many people would just replace the sensor (this would have wasted about £200), I went further to establish if the error is the sensor itself or the wiring that its connected to, I first verified the ecu wasn’t receiving any data from the sensor by monitoring live data on the computer with the engine running and compare the temperature of the other 2 sensors and confirmed it wasn’t seeing any data, and to test the wiring I used a sensor simulator which confirmed it still didn’t see any data, I then tested the wiring further down the harness and found continuity to the ecu, so the fault had to be in the harness plug there was no visual sign of a break so I gently pulled on the wires in the back of the plug the signal wire broke free as it was only the insulation that was intact the copper wire inside had broken, I carried out a repair on the wire and retested to confirm the fix.

The moral of this story is that you need to understand the system to be able to correctly assess the problem, before you can fix it, in this case a clean wasn’t required despite another garage saying it did and it wouldn’t have solved the issue.