P0345 Code

[03Merc]

Anyone have this code b4 and fixed it? I tried coil, spark plug and new coil connector. Car still running lean. Misfiring slightly.

Correction P0354 cylinder 4.





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[SilverPhoenix]

While I don't know much about fixing cars, I did a quick search and found this checklist and there also seems to be a few videos about this code on YouTube...

How to troubleshoot the issue




Inspect the ignition coil:
(https://www.google.com/search?cs=0&sca_esv=b93990c6e247b7c1&q=Inspect+the+ignition+coil&sa=X&ved=2ahUKEwiqqKXkv52QAxWhkYkEH XHmEXUQxccNegQIMBAD&mstk=AUtExfAoaioUB7bfcBnRcYDi_ 7juBddCDmfaOqa3odBUctdf3jhs5EV 4j4q50FKfNcWmKW1AqWeBpC6et9YcY jqKpDdds7R5S2QjyvwUPP_UKF5A_L2 ZjLPBEHfPc2t6Oza6YcbI9KVLLY1lD u2wkzETNarOKcFpWnYdAkaSfzaPF-VCevU&csui=3)Check the ignition coil for cylinder #4 for any signs of physical damage or corrosion.








Check the spark plug:
(https://www.google.com/search?cs=0&sca_esv=b93990c6e247b7c1&q=Check+the+spark+plug&sa=X&ved=2ahUKEwiqqKXkv52QAxWhkYkEH XHmEXUQxccNegQIPhAD&mstk=AUtExfAoaioUB7bfcBnRcYDi_ 7juBddCDmfaOqa3odBUctdf3jhs5EV 4j4q50FKfNcWmKW1AqWeBpC6et9YcY jqKpDdds7R5S2QjyvwUPP_UKF5A_L2 ZjLPBEHfPc2t6Oza6YcbI9KVLLY1lD u2wkzETNarOKcFpWnYdAkaSfzaPF-VCevU&csui=3)A failing spark plug can also trigger this code. Inspect the spark plug for cylinder #4.








Inspect the wiring harness:
(https://www.google.com/search?cs=0&sca_esv=b93990c6e247b7c1&q=Inspect+the+wiring+harness&sa=X&ved=2ahUKEwiqqKXkv52QAxWhkYkEH XHmEXUQxccNegQIPBAD&mstk=AUtExfAoaioUB7bfcBnRcYDi_ 7juBddCDmfaOqa3odBUctdf3jhs5EV 4j4q50FKfNcWmKW1AqWeBpC6et9YcY jqKpDdds7R5S2QjyvwUPP_UKF5A_L2 ZjLPBEHfPc2t6Oza6YcbI9KVLLY1lD u2wkzETNarOKcFpWnYdAkaSfzaPF-VCevU&csui=3)Examine the wiring and connectors leading to the coil for cylinder #4. Look for loose, frayed, or damaged wires.








Test the coil:
(https://www.google.com/search?cs=0&sca_esv=b93990c6e247b7c1&q=Test+the+coil&sa=X&ved=2ahUKEwiqqKXkv52QAxWhkYkEH XHmEXUQxccNegQIPRAD&mstk=AUtExfAoaioUB7bfcBnRcYDi_ 7juBddCDmfaOqa3odBUctdf3jhs5EV 4j4q50FKfNcWmKW1AqWeBpC6et9YcY jqKpDdds7R5S2QjyvwUPP_UKF5A_L2 ZjLPBEHfPc2t6Oza6YcbI9KVLLY1lD u2wkzETNarOKcFpWnYdAkaSfzaPF-VCevU&csui=3)Use a multimeter to test the coil's resistance and ensure it is functioning correctly.








Repair or replace:
(https://www.google.com/search?cs=0&sca_esv=b93990c6e247b7c1&q=Repair+or+replace&sa=X&ved=2ahUKEwiqqKXkv52QAxWhkYkEH XHmEXUQxccNegQIJBAD&mstk=AUtExfAoaioUB7bfcBnRcYDi_ 7juBddCDmfaOqa3odBUctdf3jhs5EV 4j4q50FKfNcWmKW1AqWeBpC6et9YcY jqKpDdds7R5S2QjyvwUPP_UKF5A_L2 ZjLPBEHfPc2t6Oza6YcbI9KVLLY1lD u2wkzETNarOKcFpWnYdAkaSfzaPF-VCevU&csui=3)Based on your findings, replace the faulty ignition coil, spark plug, or repair any damaged wiring.








Clear the code:
(https://www.google.com/search?cs=0&sca_esv=b93990c6e247b7c1&q=Clear+the+code&sa=X&ved=2ahUKEwiqqKXkv52QAxWhkYkEH XHmEXUQxccNegQINxAD&mstk=AUtExfAoaioUB7bfcBnRcYDi_ 7juBddCDmfaOqa3odBUctdf3jhs5EV 4j4q50FKfNcWmKW1AqWeBpC6et9YcY jqKpDdds7R5S2QjyvwUPP_UKF5A_L2 ZjLPBEHfPc2t6Oza6YcbI9KVLLY1lD u2wkzETNarOKcFpWnYdAkaSfzaPF-VCevU&csui=3)After making repairs, clear the code and take the vehicle for a test drive to confirm the issue is resolved.

[03Merc]

I figured it out, hairline crack in the spark plug, I had a couple extra on hand. Just drove the car 700miles round trip. Will throw in fresh new plugs next oil change.

Thanks for the info! Will keep this on hand for future.


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[SilverPhoenix]

Glad I could help. Finding a hairline crack in a spark plug...I would have never thought about that being a possibility.