Hard to start engine now Engine light on again

[kowboy]

2004 Mazda 3 2.3L Auto Hatch 148 000KM

Oil and filter done around 147500km mark. A month ago engine light came on, took to mechanic and changed O2 sensor. During holidays car sat in drive for about 10days and would not start. It would crank and try to turn over and then every light would alternately flash on and off. Jumped battery and let run for 20min then took to mechanic. They swapped out the battery. As I was driving away the engine light came on, mechanic did a scan and the scanner kept coming up with no fault found.
Every morning, (it's winter now) it is difficult to start, slow cranking, lights flash n dash and finally starts. It has stalled at stop lights and going in reverse. Engine growls very loud on cold starts and on acceleration (had engine mount replaced last year) but seems to go away after being on for 15-20min. My commute is not far 7km one way.
Now today engine light is back on. I have not taken to mechanic yet. Any suggestions?

[Lockdown]

Where are you located?

[stevenma188]

Strange that you have a Check Engine Light but no code.

[a_ahmed]

TDC timing issue? We had the same issue when we swapped replacement engine for me.

[kowboy]

Don Mills.

[Lockdown]

Still have codes? Or more specifically CEL?

[kowboy]

Had CEL for past two days since posting. Got off work early to take car in and guess what CEL disappears. But the slow crank starting is still present with alternating message lights on dash while trying to start.

[krimsalt]

Could be crank position sensor.

[Lockdown]

Might need a better scan tool but if you want to come by, I'll scan it

[kowboy]

Just an update, went back to garage, they had put in a defective battery, so gave me a brand new one. Also driver and rear engine mounts were gone, causing all the vibration and rattling. My M3 is happy again and purring perfectly. Thanks all.