Powertrain
Definition only
Lights the check engine lamp
P28B9: Cylinder 11 Ion Current Sense Circuit Range/Performance
Standardized SAE J2012 code · P28xx codes
What does P28B9 mean?
The ion current signal from cylinder 11 is outside the expected range for combustion conditions. Combustion quality cannot be assessed reliably.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Common causes
- High Spark plug aged - electrode shape changed
- Medium Ion sense circuit gain drift
- Low Sensor element aged beyond calibration window
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of P28B9 on the same make and model first.
P28B9 in the community
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Describe your P28B9 problemRelated codes
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- P28A5 Cylinder 6 Ion Current Sense Circuit Range/Performance
- P28A9 Cylinder 7 Ion Current Sense Circuit Range/Performance
- P28AD Cylinder 8 Ion Current Sense Circuit Range/Performance
- P28B1 Cylinder 9 Ion Current Sense Circuit Range/Performance
- P28B5 Cylinder 10 Ion Current Sense Circuit Range/Performance
- P28BD Cylinder 12 Ion Current Sense Circuit Range/Performance