Faults Stored on Engine Control Unit:
P0237 – Boost Pressure Sensor Signal Too Low
P2463 – Diesel Particulate Filter Partially Clogged
I was booked to clean the dpf on this vehicle, I always carry out my own Diagnostics which involves more than just reading the fault codes these are only meant to give you a starting point where to start looking for a problem.
The DPF is always the victim so it is important to find the cause first as cleaning alone doesn’t solve the problem, in this case the owner bought the car with the boost issue but no dpf issue at the time, the garage that sold him the car said they would fix the problem and they replaced the Map sensor & turbo vacuum transducer (N75 Valve) which didn’t solve the problem the owner continued to use the car unaware that the DPF can not regenerate with this issue which led to the DPF becoming blocked, the garage wrongly informed the owner that the dpf issue needs to be fixed before they can fix the boost issue that they had so far failed to fix.
My diagnosis involved testing the Map sensor circuit as the ecu wasn’t being provided with the manifold pressure signal so the car was driving in super limp mode, in my tests I established there was no 5v reference voltage going to the sensor so I tested this by providing a 5v feed to the sensor which confirmed the sensor was ok, I then Cleaned the dpf as it was to blocked now to carry out a Forged regeneration, I then carried out a forced regeneration with my Professional diagnostics equipment the car is now fixed and fault free.
The owner had taken the car to several so called specialists with diagnostic tools well capable of doing the work but what they lacked was expertise to use the equipment to find and fix the real problems.