[Nickthecook]

I've had very similar issues to you with my 06 D5 185. Firstly, Volvo kept very quiet about the type of EGR they fitted to the Euro4. It's a Ford designed High Pressure Loop EGR that works by creating a pressure differential between intake and exhaust by using the Throttle and the Turbo Vanes. In my opinion, it is missing a failsafe as it doean't have any way of measuring the EGR/Fresh Air Mix. Instead it relies too heavily on calculated values. If, like you and I there's a unusually high DPF pressure reading, the EGR system compounds the problem.

Back to the cause if your woes. I'd get a multimeter and check the single ECM power supply from the Alternator. Although you don't have other DTC's, I wouldn't mind betting your other sensor reading are all to **** due to insufficient voltage to the ECM. While your there, check the power steering pump for any leaks. This can drip into the Alternator and get onto the brushes. I replaced the connector an the single wire that plugs into alternator and saw an improvement, however there still seems to be an issue. When I back probed the connector, I got a rapidly fluctuating voltage of between 3.5v and 8v, with the connector off I got a solid 12v. However, I foolishly forgot to check it after replacing the connector and suspect the voltage is dropping under load.

Before replacing the connector, I was seeing idle How reading of anything from 60hpa to over 100hpa. These spiked massively with a bit of boost. I suspect the Volvo Sensor has a far greater tolerance, as the original on mine only ever produced produced one DTC, which cleared and didn't return after replacing the DPF. However, when the 'Soot Filter Full'Messages returned after only 7 months, I took the sensor off to check for moisture and the HI side nozzle (large diameter) crumbles in my hands. When I put a new Sensor on, like you I had the Sensor Low to start. However, the difference on the Engine was unreal. What I had assumed was engine wear, was all down to the old sensor. The car was quieter, smoother and by God did the power return. Sadly though I was getting one fault after another for the sensor and 'Particulate Trap.' I saw you had a silly reading after blowing in the narrower tube. Was this 65535 by any chance? This is the maximum value that can be calculated by a 16bit processor. It basically means the voltage is out of range by a country mile. I suspect a very low signal voltage. The Sensor High fault that follows is purely the ECM goung through the motions, probaly to force a regeneration (EGR 95%, or 94.9% on Torque Pro. You will no doubt be having EGR and Throttle issues too. If it's the ECM power supply, every single sensor module will be out by a mile, or in the throttles case, working in reverse. The only reason I dropped on the power supply issue was down to getting a RED Triangle and 'Brake Failure' Message this morning. It suddenly reminded me of an issue with an Octavia I owned, when the batteries charging supply from the alternator burnt out and every single warning light came on.

A little tip, don't use the Engine to brake until it's fixed. My throttle kept moving to 90% closed on both lift off and anything more than a feather on the accelerator. This creates a significant vacuum after the Throttle Body/EGR and it won't be long before you're sucking the oil past the piston rings. Once the electrical issue is sorted, I'd advise a forced regeneration and counter reset so the ECM knows where it is. That info is used to calculate exhaust pressure for the EGR System and with incorrect data, you'll have further problems down the line. Please keep me posted on how you get on, I'd be really interested to know.