Hi all, came back from holiday today and started my car. Engine light, tire pressure light and stability light all came on. After a while, engine light started flashing and car started sputtering.

Code came back 0300 and 0302 and 0304 (0300 random misfire, 0302 misfire on cylinder 2 0304 misfire on cylinder 4). Replaced all 4 spark plugs. Codes came back 0300 and 0302, 0304 was gone. Swapped the cylinder 2 coil with cylinder 3 coil to see if it was the coil and error codes then came back 0300 and 0303 confirming my suspicion. Swapped them back and got 0300 and 0302 again. This to me suggested that the coil that was currently on cylinder 2 was faulty.

Put in a brand new coil on cylinder 2. But codes still came back 0300 and 0302. Once again I swapped the new coil on cylinder 2 with the old coil on cylinder 3, so the new coil was on #3. Code then came back 0300 and 0303.

It would just be too coincidental to have gotten a DOA coil… but I suppose its possible. I can’t think of what else would cause the code to jump like that… if it was wiring it would stay regardless of what cylinder the coil was on.

Is there something I could be missing?

edit to add: I kept the wiring consistent; ie when I swapped coils, I kept the wiring harness with that cylinder instead of swapping wiring and coil together

 

did you analyze this issue with a professional before or it's your first time ?

 

First rule of DIY service is NOT replace any parts that you have not first varified they have failed. Doing so more often then not creates additional unresolved problems.
Your DTCs indicate not only direct ECU DTCs but also anomalous one unconfirmed or out of programing to designate a specific DTC problem area. t
You did not mention checking the condition of the battery. This means doing or getting it load tested.
I would also have looked carefully at the ground lead both at the battery and at the point of grounding to the body/frame.

Action in this sequence:
Load test Battery
Check all the battery connections. Specifically, the grounding cable at battery and at the body/frame attachment point.
With a OBDII scanner connected to the OBD diagnostic connector retrieve all current DTC
Clear any and all DTC
Go to monitors note if any are not in state of readiness and reset the monitors.
Strat or attempt to start the engine.
If no start after 15 seconds go back into the ECU and retrieve the current DTC.

DO NOT RUN THE STARTER MORE THEN 15 WITH A NO START

Then you can report what you find out here?