Hi, my 09 diesel auto occasionally behaves as though it has misfired, just the once, and then carries on performing normally, general running, fuel economy, and starting is all good, I can’t deliberately make it happen and it doesn’t do it every time the car is used, any thoughts before I trouble a garage to get it plugged in ?

Common problem without a fix https://www.freel2.com/forum/post383424.html#383424

Yes I’ve read that thread, only thing is they are nearly all post 2010 vehicles, mines an 09 So not sure if any of the suggested soloutions apply, and mines only just started doing it at around 83000 miles.

I had this problem with mine and it turned out to be an air leak in the fuel line running from the diesel filter to the high pressure pump. Pull back the black plastic covering on the hose protecting the line and give it a shake around the connection on the fuel filter housing and if it is the problem you will probably see a line of air bubbles running through the hose followed by a misfire.

Had this problem on my 08 manual. Changed fuel filter, no difference. Changed crankshaft position sensor 18 months ago and never did it again.

I had this problem, it would hiccup, like a single misfire but mine developed into an occasional stall.
Took it to my local indy who wrongly diagnosed the fault and changed a unit (Can't remember what it was)
as I was driving away it did it again so I turned around and took it straight back.
To cut a long story short, I ended up leaving it with them for two weeks. Eventually, they changed the crank sensor and that was it.

Turned me right off my local indy because I got billed for things that he caused while he had it.

Just had to have the EGR changed but didn't go anywhere near the indy for it

Thanks all, still have the issue but am now more confused than ever, I bought a generic oem crank sensor from a very well known LR parts specialist, fitted it and the car would not start, turns over ok but then stops and has ‘reduced performance’ on the dash, refit the original sensor and the car starts straight away. I contacted the parts outlet, got credit for that part and bought a genuine LR crank sensor, just fitted it and it does exactly the same, car won’t start, reduced performance on the dash, refit the original sensor and the car starts straight away ! Am I being thick here ? Do I need to follow some sort of procedure after fitting a new sensor ?

Might be worth comparing the two sensors:

https://www.freel2.com/forum/topic35054.html 
Hung like Einstein, smart as a horse.

A quick search on here found a post that mentions that there are a few versions of crank position sensor that all fit, some have different wires going to similar pin patterns and plug shapes. You need to make sure you’ve got the correct version as some fit but don’t connect up correctly.

I replaced mine and bought it from Duckworth. The part number does vary so I provided my VIN number and had no issues.

Further information, the ‘genuine’ LR crank sensor they supplied was in an open box, and looks like it may have been used previously, part number LR056028, it has fomoco, PA6.6, and some smaller numbers on it, the pick up head is a different shape to the one on the car that works, the electrical plug socket is identical as are the pin numbers imprinted inside. Is there any way of finding out if it’s the correct part for my car. Ive already emailed the suppler to complain about them selling used parts as new, no response yet today..