Revs cutting around 3k but no CEL or codes, ideas on where to look?

[Whitey]

As above. My 2010 Evora is on 46k miles and on the last couple of runs out, on start up, the spanner light has stayed on for longer than normal but then goes out after 30-60 secs. Driving the car from cold I never rev it high until it’s warmed fully, so it’s not that. Engine still sounds as sweet as normal with no rough running or misfire, it’s still running on all 6 cylinders but just cuts at variable points around the 3k mark. No warning lights at all. My Autel code reader didn’t detect any codes. On the return trip yesterday when the car was fully warm, it didn’t happen and I was revving it to around 5k, but didn’t want to chance it further!
car was serviced about 500 miles / 2 months ago by Williams- and I’ll be speaking to them later to see if they can point me in the right direction.

Just hoping someone here knows what this could be, and what the cure is.

[Bibs]

I think there are 2 engine temp sensors, perhaps the one that feeds the ECU is on the way out. Have you got a code reader, that would tell you the ECU's temp sensor reading. 

[Whitey]

Not sure if my code reader will read that, but thanks for the pointer. I’ll try the car again this morning and speak to Williams on Monday.

[Bibs]

If it's one that connects to your phone, load up the Torque app and you'll get real-time engine data

[DH2]

Spanner light indicates electrical fault that doesn't affect engine running or emissions, and will either go out straight away after starting engine (normal operation), or stay on for 30s to indicate a fault is stored.

You need to read the code, but this may not be possible on generic OBD.

Dave

[Whitey]

Thanks Dave, I took the car out twice today and revs were fine, no cutting out at all. Spanner light is still staying on for 30secs, so I’ll nip over to Williams for them to plug it in and see what codes pop up 👍

[Whitey]

Update:

I rang Williams and they booked the car in 2 days ago to plug it into their Lotus diagnostics system. Not being a Lotus main dealer anymore, they have to now rent usage of the System by the hour / day/ week etc from Lotus, and I believe it is a slightly “lighter” version of the full fat main dealer system.

However, after cleaning the maf sensor and checking the engine for any vacuum leaks when they plugged the car into the diagnostic system it brought up 2 codes:

CO340 - brake light switch, which I was aware of and had a new switch in the car for them to fit.

P1809 - clutch position noisey, new sensor required.

So they fitted the new brake light switch and I will source a new clutch position sensor and return for them to fit it.

They cleared both codes and the car drove superbly on the home trip.

Top marks to Williams autos again for fitting me in at short notice and sorting all the above in 1 hour. 👍