2018 CX-9 P0303

[Frozendog]

Hi,

2018 CX-9 147k kms throwing P0303 code only in idle. Plugs and injectors changed and good. Mazda nor I can figure out problem. Mazda says it may be carbon on valve or in chamber, anyone have any ideas because I have no solution? It drives fine but I cannot sell like this and don't want engine dammage. Thanks...

 

[22GrayGhost]

This info is from co-pilot AI

The P0303 code in a Mazda indicates a misfire in cylinder 3. If this issue occurs only at idle, it could be due to several factors, including:

• Faulty spark plug or ignition coil in cylinder 3.
• Clogged or faulty fuel injector.
• Vacuum leaks affecting air-fuel mixture.
• Low compression in cylinder 3.
• Incorrect fuel pressure.

A good first step is to check for intake leaks and inspect the spark plug and ignition coil for damage. If those seem fine, further diagnostics may be needed to pinpoint the issue

 

[Frozendog]

Hi, thanks for the reply. Spark plugs new and checked, all good. No ignition coil. Fuel injectors new and checked, all good. Compression checked, all good. Brand new fuel pump following recall replacement, so all good.
I don't know about vacuum leaks.