I was driving and stopped in traffic on a slight hill at 70degF nice cool day engine wasnt quite warmed up yet after 7min driving. Fault hasnt occurred before.

Next thing i know the engine cuts off. On restart terrain options not available and shifter stuck in F fault mode (which means the manual sport mode select options are not available and terrain response cannot be selected). The car is fully drivable but with limited gears.

Upon parking and cycling the ignition a few times and turning on off the engine a few times, 3-5, pulling the key out putting it back in faults disappear.

So i ran the codes and the coolant sensor thats installed in the thermostat (and which i had just replaced a year ago), could it be causing issues of engine just cutting out, or misbehaving?

The other lost communication faults can all be ignored typical LR3 message spam.

1. battery voltage is good and its new
2. alternator is good and new
3. all the grounds i redid a year ago and are clean corrosion free, plus no other electrical issues experienced in a year
4. the fact that the fault can be reset means its intermittent and situation dependent (voltage, temperature, quantity, pressure, current, incline on the road (since i was at a stop at zero speed) etc)
5. thermostat has not failed open since its new and it heats the inside of car
6. coolant and oil level is good
7. car raises and lowers on air suspension normally and no airstrut leaks
8. car locks unlocks normally and have already replaced the hood switch, the brake switch

Any ideas?

 

If it's disconnected the car will not start. If running it will be absolutely terrible running, loosing power and cutting out. So a fault with it could cause drive-ability issues

 

I've got that fault also. Can't figure out what it is. The gauge on the dash reads correctly and the engine runs fine.

 

Figured out the engine turning off or not starting issue that appeared randomly one day on my Landrover LR3 2008 V8:
1. i replaced the coolant sensor but that didnt make a difference.

Solution: the engine relay - go figure. relays dont fail like light bulbs so when they fail its more of a sporadic contact closes or opens while driving situation, in my case for some reason the relay must have disconnected my ECU just so, hence the engine switches off or doesnt start, $20 fix, put in a new engine relay, i think they are 40-60 amp not sure, also i went through the engine fuse box and cleaned the contacts of all relays and all fuses just to be on the safe side and i havent had any issues for a couple days now, crossing my fingers, if they dont recur after 2 or more months then i resolved the intermittent fault (i switched the R9 window heater relay with the R6 engine electrical relay);



link to relay: <https://www.roverparts.com/electrical/relays-flashers-connectors/YWB500220G/>

 

Not to mentions relays are solenoid driven. Solenoids do "burn out" and get weak, hence the failure of the transfer case solenoid or when rebuilding a suspension valve block does not work but replacement does. Relays could almost be a 10 or 20 year maintenance item, just replace em all. They are just bog-standard relays after all.