[endrick]

I am hoping someone has had a similar experience and can help.
ESP warning light would come on and engine would run really rough
Replaced Brake switches to no avail
Plugged in to computer which said ABS pump was faulty.
Pump was sent off to a specialist company for testing and came back as no problems found.
Problem became worse with car breaking down completely when the engine had heated up  but would re-start after 30 minutes.
Mechanic thought it was either a wiring issue or a ecu (computer) problem and offered no further diagnosis .
I read up on some Hyundai problems , saw that some cars had problems with crankshaft sensor.( What function a crankshaft sensor  performs  I have not a clue)
I asked my mechanic to try replacing the crankshaft sensor.
Since doing this the cars seems fine although I have not risked a long run with it.
However, now the alarm goes off intermittently. Has the crankshaft sensor now spooked the alarm system I am wondering?
I`m also wondering why bother with all this technology and sensors. We had a Hyundai Accent for 10 years with none of this tecnology  and it proved to be the most reliable car we ever had . Hence the reason we bought another Hyundai. This i30 is now ranking towards the bottom of car reliablity on our list of past vehicles.

[Dazzler]

Welcome endrick,

Sorry to hear that. Yes, electronic complexity can cause issues at times. All brands have gone this way unfortunately, not just Hyundai. The i30 has still proven (generally) to be one of the most reliable cars on the road.

What model and year is it. Manual or Auto?

I'm guessing it is out of warranty.

I will wait for other more mechanically savvy members to help with yourr issues, but they may need more info about the car. 

[endrick]

FURTHER INFORMATION:
YEAR: 2009
MILEAGE:72,000
MANUAL, 5 Speed , Saloon
OUT OF WARRANTY : It was never taken to dealers for servicing , but serviced regularly by experienced mechanics
Thank You kindly for your comments.
Yes any expert mechanical advice from a Hyndai specialist would be useful unless if it is not forbidden to divulge such
statistics and information please.

[nzenigma]

Crank and cam sensors are common to any new motor. the alarm seems  coincidental .
What alarm are you referring to? Anti theft , door open, seat belt ? Does it happen while you are driving or in bed?

[endrick]

The Alarm Problem:
The problem is in relation to anti-theft.
I did not know the car had such a system till this malfunction occurred.
Strong wind seems to set it off and
If I leave the locked , it  goes off. 
So the current remedy is to leave the car unlocked,
but this is obviously not a satisfactory remedy.

[Dazzler]

Thanks for the extra info @endrick

Our "technicians" are generally not affiliated with Hyundai and this is an independent non profit forum.

There are no restrictions on the information we supply. Hopefully some others have insight which may help you.

With a bit of luck (as Garry has suggested) it might be just a case of changing the bush and getting the code reset. 

[nzenigma]

The Alarm Problem:
The problem is in relation to anti-theft.
I did not know the car had such a system till this malfunction occurred.
Strong wind seems to set it off and
If I leave the locked , it  goes off. 
So the current remedy is to leave the car unlocked,
but this is obviously not a satisfactory remedy.

Until you find the maladjusted door sensor, Just lock it with the Key, don't use the remote.

[yodm]

about the alarm:
by your description, its either one of the doors sensors (but than the cabin light will be turned on as well and you will have warnings for open door during the ride), or the hood sensor, if it started after the crank sensor replacement the mechanic could have un-knowingly touched it and now its seating a bit too low. try and push on the hood and see if it makes any change. my previous Citroen had this issue, the anti theft alarm have a separate switch for the hood. or one of the pressure sensors in the cabin is is facing directly the window (if you have the small thingies on both sides of the front window)
about the crank shaft position sensor:
this sensor reads the position of the crank shaft and this signal is set to time the ignition system with other signals from other sensors.
when this sensor starts to send unstable signal, you will have rough engine running, no RPM gauge, "ESP off" light on, engine will die on traffic lights and sometimes when you take your foot off the throttle. then you will have hard starting and all of the above symptoms.
you said your engine over heated? if so, it could be that the car was not serviced right all over the years and now you will start to experience all sort of troubles and issues. 

[nzenigma]

Thanks Yodm, I was a bit pushed for time and didnt mention the hood button which, as you say, is the most likely culprit and mechanic has moved it. Also check its rubber stopper is still in place RH side of engine bay.