We did a 100 miles round trip recently, but on the return journey car started a regen, but then it started to act up, it would not drive properly in 5th and 6th gears, felt like it was in too high a gear and had to change down (this was at 60mph to 70mph) and was accompanied by what we can only describe as a grumbling/growling noise from what sounded like it came from engine bay (but could have been from gearbox front area) with an occasional knocking from the exhaust at the rear end. Got home and left for a day, then short trip to shop and regen carried on for 10 min after getting back. Later took it out and once car was warmed up the problem returned but this time 4th gear was also affected. Car is 2014 140 4x4 with 36,000 miles on clock. It has been running fine until this happened. Any suggestions to probable cause would be gratefully appreciated, I am not mechanically minded and disabled, so I can't get under the car to have a look. Thanks for any reples in advance.

A couple of things to check:

 

1) Can you check the oil level in your car please?  If its low on the dipstick, then top up with 504/507 grade oil.  The car could be restricting power in that direction.

2) Ditto - please check the coolant - an overheating engine will also cause power loss issues.

3) What fuel do you drive with?  I know that Diesel is the correct answer, but I wanted to know if you are driving on supermarket fuel or not.  If you are running of supermarket duels, please change to a branded fuel with cetan improvers in it [Esso, BP,Shell etc].  The loss of power could also be caused by a partially blocked DPF (or Diesel Particulate Filter).  My current favorite stuff is a product that you put into the diesel tank after refill - is Hydra International Diesel Power Blaster which librates the TDI engine and clears out a mass of gunge and tutt from the DPF.  You will also need an oil change afterwards.

4) When was the last time the fuel filter was changed?  At 36k miles, I would have expected this to be done on around the 2 or 3 year old mark.  A blocked filter will cause fuel restrictions and make the fuel pump work harder.

5) Sorry - this last one may seem harsh if you care for your TDI engine, but they need a good 'Italian Tune-up' occassionally - and a good 100 mile journey with higher revs to really clean out the engine.  If a re-gen occurs, it needs heat and lots of it to burn up the soot in the DPF.

 

In terms of the excessive noise; you could also have a leak from the exhaust manifold or from the exhaust system itself (which would reduce power via the positive pressure the engine needs to maintain good operational running).

Probably best to check for error codes before doing anything else. Poke and hope is best avoided.

Hi, thanks for the answers so far. All oil and fluid levels have been checked and are OK. I would have thought the 100 mile round trip would have cleared the dpf, but maybe not, as it ran after the next short trip it did. I can't check for error codes but have it booked in at local garage next Monday and will insist on error codes being read, and for them to do a passive regen as well and change the fuel filter just in case. Will see if they can add something like Diesel Power Blaster and then rebook for an oil change later. Sorry, but should have added that is was occasionally getting stuck when trying to chnage down to 2nd gear at crossroads etc.

The other option here is the garage to check the oil in the gearbox if you are getting issues with changing gears. This points more to a problem with the gearbox or loss of oil if you canny change the gears easily. Did you hit an object in the road? If so, can  somebody else to check if there is an oil underneath the car? If so, it should not be driven until the damage is assessed.