We have recently had a problem with engine cutting out. It would restart but dies on revs. We have an excellent mechanic and he checked and got fault code P1345. We replaced the CPS but fault returned. We then removed cleaned and replaced the the crankshaft position sensor. Took the car for a run approx. 30 miles and all now seems OK.
During the fault problems the engine block indicator was on. Now not showing. We have an MX5 1,8 2001 Reg MX51THE.
Any suggestions or ideas would be welcome please. Car has run great for two years and has only done 55000 miles.
Well done on keeping the mileage so low!
So I’m a bit confused, after sorting the crank and cam sensors you took it for a run and it was fine, and the engine light was on but now isn’t (presumably because the fault is fixed). What’s the issue?
Following the cam replacement the fault occurred again. This was after taking the car for a run.Then we cleaned the crankshaft sensor rather than spend £75 on replacing. Guess we are waiting for the fault to show again. Maybe we have sorted it !!
Yes the Mk2.5 can have the light on. It will not go out with the erase function of the code reader and then go off in it’s own good time and stay off.
The Mk3 is the same with the ABS light coming on and going off after a 50 mile drive. The ABS still working with the ABS light on.
I know that few of us do it but worth having a set of known, working basic spares for these cars - saves a lot of hassle when there are these indeterminate types of problem.
It seems that P1345 often relates to the crank sensor and there have been occasions where the wiring to said crank sensor has got damaged by a belt for example and created this fault code.
Check out ebay - lots of used crank sensors around for around £25 delivered and for a fiver more a new part.
I understand better now.
I don’t think you have enough info right now to take any action other than monitor it (especially if when it fails, the car still drives!). If it still remains as intermittent as described I would also suspect wiring as Rhino pointed out.
On the other hand, a new crankshaft position sensor can be had from MX5parts here for £23 https://www.mx5parts.co.uk/crankshaft-position-sensor-aftermarket-mk2-25-p-4362.html
… so if it does still give you issues, it could be significantly cheaper than £75 to throw a part at it 
(I’m assuming Mk2)