Exhaust pressure sensor

The EML in my 2009 Volkswagen Passat 2.0 CR TDI came on after 93,000 miles. My Foxwell NT500 scanner – which I am not very good at using! – is giving the codes ‘001137 exhaust pressure sensor 1 (G450) implausible signal’ and ‘009299 DPF filter differential pressure sensor implausible signal’. The scanner gave the code info: ‘01137 Fault status 11100000; priority 2; freq 1; pressure -82mbar and -77mbar’ and ‘09299 Fault status 11100000; priority 2; freq 1; pressure -87mbar and -77mbar’.

I have cleared the codes and driven 30 miles so far without bringing on the EML again. I assume that it is the same sensor? If so, I suppose this could be a faulty sensor or problems with hoses or wiring. Given that I have had the differential pressure sensor replaced on a Peugeot 307 2.0 at 100,000 miles, it would seem likely to be the same thing. However, I understand it would need adaptation/calibration once fitted, and to do this I need a channel number and value to code it. I know that two part numbers were used, but mine is the later one – part no 076 906 051B.

Also, the DPF has 108ml of ash and it has been 530 kilometres since its last regeneration. How much ash can the DPF hold before it needs to be cleaned? Ian Hildrew First, I should say that all vehicles with a DPF should be using a low ash oil to extend the life of the DPF. It should be noted that ash and soot are two different products. Soot will burn off from a DPF during regeneration, whereas ash will not, as it is made up of inert inorganic metals and mineral compounds from lubricants and the result of engine wear. This will build up to a point where the DPF will become blocked. The regeneration will continue to take place but will not reduce the back pressure. The maximum oil ash volume of the DPF should be around 380ml and, using the recommended low ash oil or low SAPS (Sulphated Ash, Phosphorous, Sulphur), it would be expected that the engine should have covered nearly 400,000 miles before this was achieved.

The ‘G450’ implausible signal codes do indicate a fault with the sensor, but it is also very likely that the problem is in the wiring loom between the sensor and the ECU. Pay particular attention to the loom where it intersects with other sets of wires just above the gearbox. It has often been found that where the loom then connects to the vehicle body, the plastic insulation trunking can chafe through the wires internally. If no faults are found with the wiring, then the sensor will most likely need replacing