Powertrain
Definition only
Lights the check engine lamp
P28A4: Cylinder 6 Ion Current Sense Circuit
Standardized SAE J2012 code · P28xx codes
What does P28A4 mean?
The ECM cannot read a valid ion current signal from cylinder 6. Ion current sensing relies on the spark plug acting as an electrode after combustion.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Common causes
- High Ion sense module failed
- Medium Wiring or connector fault
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of P28A4 on the same make and model first.
P28A4 in the community
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Describe your P28A4 problemRelated codes
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