I had some problems about a month or so ago regarding whether or not to replace the engine in my Mazda 6 2.3 petrol sport (2005) as the oil pump had failed and knackered the engine (65K miles). I did decide to replace the engine and found one online for £1500 (reconditioned - Japp Auto Parts, UK). The engine arrived, the old one was taken out by a local garage and the new one put in. The old engine did still run but was a little rattly. Also of note before the oil pump issue was discovered was that there was an engine warning light flagging up a defective cam shaft sensor. From what I can gather online this is not an uncommon fault in Mazda's of a certain age. Unfortunately, the new engine starts ok and runs but only for about 5 seconds then it cuts out. The cam shaft sensor was still showing so my garage ordered a Mazda genuine part and replaced it....... the code is still showing on the diagnostic computer with no other codes. My garage are a bit stumped at the moment. They have replaced various other sensors including the crankshaft sensor (can't remember the others) and still no joy - engine runs for a bit and then cuts out. The engine supplier has been of no help and I am wondering if the engine is just a faulty one. Obviously by now my labor bill is mounting and I have no functional car. The Mazda also had a replacement clutch and water pump at the same time. Does anybody have any suggestions for what might be making the engine cut out - electrical or other? My garage said that the supplied engine looked good and seemed like a genuine like for like replacement. I should also say that the car has gone for a diagnostic at a local Mazda dealer who could tell us nothing more that the cam shaft code and then want £100/hour to look further with no guarantee of finding the problem.

I also wondered if anybody can advise me of how I stand with getting the engine supplier to sort this out; they do fit replacement engines etc. I have a 90 day guarantee so a replacement engine could be an option but I don't see why I should have to pay for another labor charge. Whether I could take the car to the engine supplier and get them to fit a new engine at their cost remain to be seen.

This is a nightmare at the moment so some suggestions would be really appreciated

Thanks