Code result
P2340
Cylinder 5 Above Knock Threshold
Moderate severity
What it means
The knock-sensor evaluation reports cylinder 5 above the knock threshold over a sustained window. The ECU retards ignition for that cylinder; persistent knock indicates poor fuel quality, carbon deposits or cooling issues.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Low octane or contaminated fuel
highOne of the most commonly reported causes for this code — check this first.
Carbon deposits raise compression locally
mediumA plausible cause — test and verify before replacing parts.
Local cooling issue at cylinder 5
lowLess common, but worth ruling out after the more likely causes.
Related help
Get the full diagnosis
Add your vehicle and see step-by-step repair help, recalls, and TSBs in Wrenchify.
Diagnose P2340 freeNo credit card required