My fiancé drives a 2005 Mazda 6s 3.0L and its throwing a CEL code of:


P0300 Random/Multiple Cylinder Misfire Detected


Am I correct in assuming the heli-coils and sparks are in need of replacement?


We already had one of the coils replaced that died on us during a road trip, I know it's bad to replace just one but it ended up being a used coil and the mech told us it was bound to fail again in the future.


Thanks in advance for your guys insight!

 

You can buy a set of 6 on Ebay for $50.00. That's the best way to go. Replace all of them at once.

 

Possible Cause/Causes, as per workshop manual.

• CKP sensor malfunction
• CMP sensor malfunction
• Ignition coil malfunction
• Ignition system malfunction
• MAF sensor contamination
• Excess air suction in intake air system (between MAF sensor and intake manifold)
• Fuel pump malfunction
• Fuel pressure regulator (built-in fuel pump unit) malfunction
• Fuel line clogged
• Fuel filter clogged
• Fuel leakage in fuel line
• Fuel runout
• Poor quality fuel
• Purge control solenoid valve malfunction
• PCV valve malfunction
• EGR valve malfunction
• Vacuum hoses damages or improper connection
• Related connector and terminal malfunction
• Related wiring harness malfunction
• Insufficient compression
• Variable valve timing control system improper (LF, L3)

 

I thought a heli-coil was a thread repair kit