P28AE code meaning
Cylinder 8 Ion Current Sense Circuit Low
Powertrain system Generic code P28xx codes Check engine light
What P28AE means
P28AE stands for an ion reading from cylinder 8 that stays too low or near zero. Either the measuring voltage never reaches the plug, because the coil's bias stage or its supply has failed, or it drains away to ground through a damaged signal wire, a wet plug well or a tracked trunk. With ion sensing the plug doubles as knock and combustion sensor, so a dead reading also takes knock protection for cylinder 8 away and the engine computer tends to fall back on retarded timing. A supply fault affecting the whole module would rather appear as P28C0 to P28C2 than as a single-cylinder code. No manufacturer documents P28AE in public; an eight-cylinder ion-sensing engine is not described. P28AF is the high-side fault.
P28AE 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 P28AE
- MIL lit with a low ion reading for cylinder 8
- Knock protection of cylinder 8 lost, timing retarded
- Possible misfire report for cylinder 8
Common causes of P28AE
- Most likelyWater or oil in the cylinder 8 plug well
- PossibleDamaged cylinder 8 signal wire shorted to ground
- PossibleBias stage of coil 8 not producing measuring voltage
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Spark plug cyl 8Ignition coil cyl 8Ion sense module
What each part of P28AE 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. |
| AE | The exact fault in that area. |
What to do next
- Note P28AE 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 P28AE
What does P28AE mean?
P28AE means "Cylinder 8 Ion Current Sense Circuit Low". P28AE stands for an ion reading from cylinder 8 that stays too low or near zero. It is a generic code, so it means the same on every make.
Is it safe to drive with P28AE?
Drive gently and only to a workshop. With P28AE the car can go into limp mode (reduced power) to protect itself.
Will P28AE fail an emissions test?
Yes, it can. P28AE 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 P28AE 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 P28AE clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.