Hi, currently sitting behind a safety barrier on a 60mph road waiting for AA.

Disco 2 V8 2004 60k miles.

Turned engine off whilst parked about 30 mins back, wouldn’t turn over when trying to start it back up. UG was showing voltage dipping from 12v down to 11v when trying to start, someone helped jump start and we left it running for 15 mins seemed fine and UG was showing 13v and healthy everything. No codes.

Driving home, after 20 mins on a 60mph hill the engine just cut out. Ultraguage first showed a symptom of engine temp ERR after the engine died, then screen went blank and obviously power steering and brakes went out.

Coasted to a safe location and pulled handbrake at 2-3 mph to stop the car.

Windows, lights, radio works but car tries and fails to start.

Crank pos sensor maybe? Alternator issue?

Extremely unnerving to be doing 60 down a steep Scottish hill towards a roundabout and everything to fail haha. Luckily no traffic today because everyone is away for the holiday!

 

Left it to cool down for past 30 mins and it now starts. Definitely crank pos sensor I think.

Open to any other things I should check so I can get started creating a list to pass the time. Spare sensor is sat on top of my workshop manual by the front door - should have kept it in the glovebox!

 

Yes, these are classic symptoms of a failed crankshaft position sensor (CKPS).

Removing and replacing the sensor itself is not difficult; it's reaching the connector that's a bugger.

Where are you located?

 

Was stuck outside the North gate at Faslane base - got a nice visit from armed Naval Police just to make sure I wasn’t up to anything

Got someone to grab my spare sensor from
the house and we (AA and myself) attempted roadside swap but exhaust was too hot to do it safely.

Let engine cool and then AA guy escorted me home with his lights at a gingerly 20mph. Going to let everything cool down and do the swap in the relatively safer environment of my driveway.

The sensor I have is a Britpart I think (wasn’t listed when I ordered it) - worth getting another manufacturer for better reliability and any recommendations?

 

I agree it sounds like a crank position sensor. A few months before mine went out, my ultra gauge was showing error messages / couldn't get engine temp readings... guessing that's perhaps a good warning indicator.

PS Buy genuine or Bosch, not the aftermarket ones. Very important.

 

Thanks for the tip - ordered a Bosch one off eBay and I’ll keep the Britpart as an emergency spare in the vehicle for the future.

Funny how everything starts failing just a few weeks after purchasing and driving a vehicle when it miraculously ran without any faults for years beforehand

First XYZ now CKPS - trying to predict and prepare for what decides to go next!

Something I am pleased with though - replaced my entire cooling system and swapped to an inline 82C thermostat setup and waterless coolant. 24C today and doing 60 (on the way out before the disaster) hovering between 78C and 82C.

Was a royal pain in the backside flushing the entire system to prep for the waterless stuff but seems like it paid off. Highly recommend the inline thermostat modification if anyone hasn’t done it already.

 

For the record, your thread title says "... Won't turn over". That term means that the starter motor will not engage to rotate the crankshaft. A failed CKPS does not do that. A failed CKPS results in the ECM (engine control module) not triggering fuel and spark because it doesn't know the position of the crankshaft (can't "see" it).

Was the engine in your truck not turning over, or was it turning over and not starting?

 

So turning the key fully and holding it there would make the 'turning over sound' but the engine would not trigger/start. I think I confused cranking and then 'successfully turning over' as two separate things when they mean the same thing, and neither describes actually starting the engine.

Appreciate the clarification so I can correctly describe the issue in the future. I am new to working on my own cars - handy at engineering and mechanical work but pretty uneducated when it comes to terminology and names of various parts/processes.

 

For what it's worth I never got the turning over and cranking thing. When someone says turning over I think the exact same thing as cranking. If it starts to run I consider it firing or running, not turning over. What I did to start it was quite literally turning it over... And over, and over haha.

 

There is no difference. Both "turning over" and "cranking" mean the same thing.