RS 275 shuts off randomly

Hi everyone,

Fresh owner of an 2015 RS Trophy which has one of the most absolute weird symptoms I've encountered in a car.

So the car essentially dies randomly while driving and won't start or will die again shortly after.

Absolutely no issues with cold starts, engine power is fine, but after around 30 mins or so of usage, the engine stops, I still have dashboard/radio lights, no errors. If I lock the car and let it be for couple of minutes it usually starts again but will just die on me again within minutes or seconds (it's a lottery).

As a bit of context, sometimes when the car does not die on me and I stop the engine voluntarily, the dash dials remain in the same position as if the car would be turned on (RPM needle at ~850 RPM and fuel tank needle). What I would do is to reinsert the card and the dash would reset to a zero position , else, if I would leave it be and lock the car, the dash light and needles would stay lit which most likely would eat up the battery over night.

No errors on an official Renault tester, checked all fuses, previous owner changed battery and the "Unite Control Habitaclé" last year, problem persists.

Initially I went to a mechanic since I was suspecting the fuel pump but the car is not lazy, mpg is normal, he was suspecting the immobiliser and sent me over to a guy who was specialized in Renault computers and he said that the ECU, UCH are fine and since there are no remaps installed on it and no errors in the tester, symptoms indicate a sudden loss of power preventing the ECU to log anything.

I also have the auto start/stop function disabled and he said this shouldn't impact or have this behaviour.

Tonight, luckily I had just parked the car, but haven't turned it off to let the turbo cool off for a sec and got out of the car to get my stuff from the trunk in the meantime. I noticed the number plate light flickering like Christmas tree and few seconds later car did its thing and engine died. May this be related to the issue I'm having?

Forgot to mention, when I'm pressing the start button after it dies, it does nothing. It doesn't try to turn the engine over, doesn't try to charge the fuel pump, it's like I'm not doing anything.

Oh and one time the car died on me on a traffic light, I left the card inserted and not pressed anything (car was in neutral, I was busy calling someone to pick me up) and literally turned itself back on without me pressing any buttons/pedals.

It's like it's possessed... I will preventively change the camshaft and crankshaft sensors (I had another 1.6L Mk3 Meggy which had a similar issue) but in that case the starter was trying to crank it and won't die on me once engine runs so it's not the same situation.

I will book an electrician soon, but just wondering what else can I ask him to check/go after besides wiring as I'm running out of ideas and tired of just spending money on "I don't know's".

Very not fun having a 1400kg piece of metal with no engine running at 60kmh...

Thanks

 

thanks a lot @Zoto and @autronix really helpful!!!

update so far: went to a mechanic to change the oil and filters and asked to tighten the gearbox earth while at it, wasn't loose but it got tighten a bit more so i had my hopes up, checked and cleaned the relays - seems the stuck tacho issue is now gone, they go down when shutting off the car myself or itself. (around 10 stops and no issue, usually 4 out of 10 stops needed me to reinsert the card to reset them to 0 position previously).

car still died at around 30 min mark this night, behavior is a bit different now. died while driving (as expected, kinda used to driving on sidewalk lane side at this point) what is changed is that the engine light flashes 2 times (it dies the first time and i think the ECU tries to restart the car but it just doesn't and thus the second flash), dash stayed lit, being at night and in a dark area i could clearly see there wasn't any difference in dash intensity and also headlights were working fine.

Everything electronic was working normally, the car just won't start (i even had power steering - not sure how, the engine was definitely off, was driving with the windows down and could clear if the engine would have been running).

Same old story, pressing start button, nothing happened. Got out of the car, closed it, re-opened, got back in, dials and everything else were working fine, just won't start (no sound of the fuel pump loading up, it's as i'm not pressing the button).

Got back off, let it be for 15 min, got back in, it started no probs, then died within seconds - power steering was working which helped parking it better. Let it be for another ~45 mins, got back in, started with no issues, got home (~10 min drive) as nothing happened.

No errors, nothing, but having the engine light popping up before cutting out is leading me to change the lambda probe sensor which i will order soon and makes me circle back to maybe a fuel pump/filter issue which I initially suspected. Again, all of my expertise and self-suggestions come from having owned the 1.6 L 16v 110hp 2009 Coupe Meggy which had its fair share of abuse in 8 years of ownership and having to go through the quirks of identifying what was the issue with what sensor so I'm inclined to believe that the real deal of its version might still have inherited bit of these quirks but the behavior and cars are ultimately not the same although the symptoms are sometimes comparable.

Since the first events, it's sort of an improvement as the car dies around 30 min mark regardless of temperature (thought this could be the issue as in an overheated ECU - ~35c in daytime, but night time is ~16c, still dies within the same time frame). Doesn't care if you drive it like an old lady or redline it, doesn't care if you are driving or just idling in a parking lot, all it needs is a working engine to shut off around 30 min of usage. If it has a coin slot where I need to put some spare change to keep having fun with it for extra time let me know...