P2350: Cylinder 9 Pressure Variation High
What to do
Often stored before anything is felt — which is the point. The suspects are the misfire suspects for this cylinder (injector first on a diesel), investigated early while the fix is still one part.
What this code means
Cylinder 9's pressure trace is varying too much from cycle to cycle — combustion that fires strongly one stroke and weakly the next, which is instability the ordinary misfire monitor only catches once it becomes severe.
Cycle-to-cycle variation is the earliest mechanical honesty an engine offers. A healthy cylinder burns almost identically every stroke; an injector beginning to lace, a glow plug fading, compression starting to leak — each shows first as inconsistency, long before it becomes a countable misfire. So this code is best read as the misfire family's early-warning sibling: the same suspects as P0309, caught sooner and named per cylinder.
Likely causes
Start here
- Failed fuel injector · moderate
Less common
- Low engine compression · specialist
- Faulty cylinder pressure sensor · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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