P28A7 code meaning
Cylinder 6 Ion Current Sense Circuit High
Powertrain system Generic code P28xx codes Check engine light
What P28A7 means
P28A7 is logged when the ion signal of cylinder 6 is held above the upper limit the module accepts. A conductor in contact with battery voltage, crosstalk from the primary side of coil 6, or an evaluation stage driven into saturation are the typical electrical explanations. Saab's T7 V6 handled the comparable fault per bank: cylinder 6 belongs to bank 2, whose combustion line triggers Saab code P1324 when it stays above 5 V for 200 combustions; the knock information of that bank travels separately to engine module pin 62. A saturated channel leaves no room for the knock oscillations, so the module retards timing on cylinder 6. No manufacturer documents P28A7 publicly. The low-side counterpart is P28A6.
P28A7 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P28A7
- MIL with high ion signal on cylinder 6
- Less power because of late ignition on cylinder 6
- Knock on cylinder 6 may not be detected
Common causes of P28A7
- Most likelyIon conductor of cylinder 6 touching battery voltage
- PossibleCrosstalk from the primary side of coil 6
- Less likelyEvaluation stage for cylinder 6 saturated
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Spark plug cyl 6Ignition coil cyl 6Ion sense module
What each part of P28A7 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 8 | Area: transmission. |
| A7 | The exact fault in that area. |
What to do next
- Note P28A7 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P28A7
What does P28A7 mean?
P28A7 means "Cylinder 6 Ion Current Sense Circuit High". P28A7 is logged when the ion signal of cylinder 6 is held above the upper limit the module accepts. It is a generic code, so it means the same on every make.
Is it safe to drive with P28A7?
Drive gently and only to a workshop. With P28A7 the car can go into limp mode (reduced power) to protect itself.
Will P28A7 fail an emissions test?
Yes, it can. P28A7 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P28A7 to fix?
Difficulty: medium. A typical repair takes 0.3 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P28A7 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.