What exactly is limp mode

[MGSheff]

And of course, as the DPF differential pressure sensor error code is a general failure, i guess that will also be having an effect on the fuel mixture levels and reducing the possibility of a regeneration.

[MGSheff]

I got under the car today on the driveway (It was blooming cold) to have a look at the sensor / pipes / wires. It's slightly hard to get at.
The bits of pipe that you can see looked OK. The wires are in a sleeve and that looked OK. The rubber tubes are shielded from view by a metal plate. The sensor and connector are almost out of view.
Removing the DPF to get access was a non starter, however, I unbolted the DPF hanger bracket which gave a gap big enough to squeeze a hand through. Unfortunately not big enough for me to work out how to disconnect the sensor.
I could feel the rubber tubes and they felt supple.

[Laird Scooby]

Originally Posted by MGSheff

I got under the car today on the driveway (It was blooming cold) to have a look at the sensor / pipes / wires. It's slightly hard to get at.
The bits of pipe that you can see looked OK. The wires are in a sleeve and that looked OK. The rubber tubes are shielded from view by a metal plate. The sensor and connector are almost out of view.
Removing the DPF to get access was a non starter, however, I unbolted the DPF hanger bracket which gave a gap big enough to squeeze a hand through. Unfortunately not big enough for me to work out how to disconnect the sensor.
I could feel the rubber tubes and they felt supple.

Disconnecting the sensor would throw another fault on the ECU, shame you can't unbolt the DPF to see if it will run without it.

[FreshAir]

I'm no expert on this, but I would be very surprised if running the engine when stationary would create enough heat in the dpf. The engine load is very low even at 4,000rpm when not driving.

[MGSheff]

OK, for completeness of this thread, I needed the car for a job so I booked it in to the main dealers. I took it in on Wednesday with instructions to check the sensors and if necessary replace them, on completion run a forced regeneration.
They phoned me up and told me it was fixed. They did a forced regeneration and that caused the sensor error codes to disappear.
So apparently there was nothing wrong with the sensors.
Main dealers charge was £120.
The V70 is now working good and proper, limp mode is gone and it is back to full power. No dash messages.

[MGSheff]

Originally Posted by MGSheff

Just a bit of an update:
I did manage to get VIDA working. It reported the same codes that I have already mentioned as you would expect.
I checked the soot level and it reported 44g.
I thought I would have a go regenerating again on the driveway. When I clicked on the advanced tab where I expected to see the regenerate option it wasn't there.
the fuel mixture.

Also, When I got it back home I decided to have another look at VIDA and how to force a regeneration. I found a Youtube clip and these are the steps.
Login to VIDA and read your vehicle, etc.
Click on the Vehicle communications tab.
Click on the Advanced tab.
Click on the Combustion of soot particles option.
Click on small box to select option 1.
It will display warnings, read these warnings and if OK click on Yes.
Scroll down and click on Continue.
Click on the VCT2000 image. It will then open a new window for the regeneration process.
Click on Starting. It will then do the regeneration. On completion of the regeneration and the DPF has cooled down to more normal temperatures, click on Stop and close down VIDA.

[Simmy]

Originally Posted by MGSheff

Just a bit of an update:
I did manage to get VIDA working. It reported the same codes that I have already mentioned as you would expect.
I checked the soot level and it reported 44g.
I thought I would have a go regenerating again on the driveway. When I clicked on the advanced tab where I expected to see the regenerate option it wasn't there.
So, I thought I would do it myself. At tickover the soot level was 44g and the DPF temperature was about 100 C. As I increased the revolutions to 4000rpm the soot level went up to 70g. The DPF temperature started raising gradually up to 250C but wouldn't go any higher.
After 30 mins of this the soot level had reduced from 70G down to 60G and at this point I decided to abandon the process.
I guess the temperature wouldn't go over 250C due to the ECM controlling the fuel mixture.

the dpf needs to reach abt 600 deg c to regen and can take an hour plus to reach this temp in a static situation . its an aggressive process not suitable for persons with mechanical sympathy