P289A code meaning
Cylinder 3 Ion Current Sense Circuit Low
Powertrain system Generic code P28xx codes Check engine light
What P289A means
P289A applies when the ion reading of cylinder 3 stays below the lower plausibility limit. Usually the signal path is pulled to ground somewhere, or the coil no longer supplies the measuring voltage of roughly 80 V that Saab's T7 cassette keeps across each gap between sparks. A cracked insulator or heavy carbon tracking on the plug can drain that voltage as well. Saab's own documentation shows why a dedicated code helps: on T7 four-cylinders a combustion signal shorted to ground produced no specific fault code at all, so synchronisation failed and only misfire codes appeared. With a stuck-low cylinder 3 signal, misfire and knock judgement for that cylinder is lost. The high-side fault is P289B.
P289A at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P289A
- MIL with low ion signal on cylinder 3
- Misfire codes or no misfire detection for cylinder 3
- Less power because timing is pulled back as a precaution
Common causes of P289A
- Most likelyIon signal wire of cylinder 3 chafed through to ground
- PossibleCarbon tracking or cracked insulator on the cylinder 3 plug
- PossibleCoil 3 no longer builds up its 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 3Ignition coil cyl 3Ion sense module
What each part of P289A 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. |
| 9A | The exact fault in that area. |
What to do next
- Note P289A 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 P289A
What does P289A mean?
P289A means "Cylinder 3 Ion Current Sense Circuit Low". P289A applies when the ion reading of cylinder 3 stays below the lower plausibility limit. It is a generic code, so it means the same on every make.
Is it safe to drive with P289A?
Drive gently and only to a workshop. With P289A the car can go into limp mode (reduced power) to protect itself.
Will P289A fail an emissions test?
Yes, it can. P289A 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 P289A to fix?
Difficulty: medium. A typical repair takes 0.3 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P289A clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.