Powertrain
Definition only
Lights the check engine lamp
P2891: Cylinder 1 Ion Current Sense Circuit Range/Performance
Standardized SAE J2012 code · P28xx codes
What does P2891 mean?
The ion current signal from cylinder 1 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 P2891 on the same make and model first.
P2891 in the community
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