Code result
P28A9
Cylinder 7 Ion Current Sense Circuit Range/Performance
Moderate severity
What it means
The ion current signal from cylinder 7 is outside the expected range for combustion conditions. Combustion quality cannot be assessed reliably.
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
Spark plug aged - electrode shape changed
highOne of the most commonly reported causes for this code — check this first.
Ion sense circuit gain drift
mediumA plausible cause — test and verify before replacing parts.
Sensor element aged beyond calibration window
lowLess common, but worth ruling out after the more likely causes.
Related help
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