P03FB code meaning
Ignition K Control Signal Circuit Low
Powertrain system Generic code P03xx codes Check engine light
What P03FB means
Ignition K is one of up to twelve control signal lines (A to L) from the engine module to an ignition coil with integrated output stage or to an ignition module – plausibly the 11th channel, but the code standard leaves the assignment to the manufacturer. The code concerns this logic-level signal, not the coil's primary circuit (coil K has its own codes, P0361 and P2330 ff). P03FB means the signal stays too low – typically the control line is shorted to ground or the input of the output stage is shorted, so the driver never sees a high level. The coil fires wrongly or not at all; the misfire usually also sets P0300 ff, and many modules shut off injection to that cylinder to protect the catalyst. No manufacturer document available to us uses this code – it would only concern twelve-cylinder engines, whose makers publish no OBD summaries; GM and Ford tables stop at eight and ten cylinders.
P03FB at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P03FB
- Check engine light on, may flash with severe misfire
- Misfire on the cylinder of this channel, rough running
- Loss of power, cylinder possibly shut off
Common causes of P03FB
- Most likelyControl line shorted to ground (chafed harness)
- PossibleInput of the coil output stage shorted
- PossibleMoisture or corrosion in the connector
- Less likelyDriver in the engine module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ignition control kIgnition coil driverIgnition wiringEngine control module
What each part of P03FB means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 3 | Area: ignition system or misfire. |
| FB | The exact fault in that area. |
What to do next
- Note P03FB 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 P03FB
What does P03FB mean?
P03FB means "Ignition K Control Signal Circuit Low". Ignition K is one of up to twelve control signal lines (A to L) from the engine module to an ignition coil with integrated output stage or to an ignition module – plausibly the 11th channel, but the code standard leaves the assignment to the manufacturer. It is a generic code, so it means the same on every make.
Is it safe to drive with P03FB?
Drive gently and only to a workshop. With P03FB the car can go into limp mode (reduced power) to protect itself.
Will P03FB fail an emissions test?
Yes, it can. P03FB 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 P03FB to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P03FB clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.