P2304 code meaning
Ignition Coil B Primary Control Circuit High
Powertrain system Generic code P23xx codes Check engine light
What P2304 means
P2304 means the control line of coil B (cylinder 2) is held at too high a voltage – usually a short to a supply line, sometimes an internal coil fault. In VW's 2014 tables a primary control circuit counts as high once its signal voltage exceeds about 5.1–7.0 V, while the low code reacts to a current above 24 mA; the Touareg six-cylinder gasoline table (engine code CGRA) names the coils directly by cylinder number. Saab's Trionic 8 (9-3, 2003) sets P2304 when more than 2 V remain on the line while the module grounds it, an open line included. A rarer cause is the module itself: Polaris put six 2026 Slingshots on dealer hold because their ECM triggered P2304, and shipped replacement ECMs. Ford's Bronco bulletin 24-2406 lists P2304 among the codes that a PCM reflash may need to remap to the right cylinder.
P2304 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 P2304
- Check engine light on
- Cylinder 2 misfiring
- Shaking at idle, weak acceleration
Common causes of P2304
- Most likelyCoil B control wire shorted to a voltage-carrying line
- PossibleInternal fault in coil B or its built-in driver
- PossibleEngine module fault (Polaris Slingshot 2026: ECM replaced)
- Less likelyInterrupted control line on systems that report it here (Saab Trionic 8)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ignition coilCoil driverIgnition wiring
What each part of P2304 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 3 | Area: ignition system or misfire. |
| 04 | The exact fault in that area. |
What to do next
- Note P2304 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 P2304
What does P2304 mean?
P2304 means "Ignition Coil B Primary Control Circuit High". P2304 means the control line of coil B (cylinder 2) is held at too high a voltage – usually a short to a supply line, sometimes an internal coil fault. It is a generic code, so it means the same on every make.
Is it safe to drive with P2304?
Drive gently and only to a workshop. With P2304 the car can go into limp mode (reduced power) to protect itself.
Will P2304 fail an emissions test?
Yes, it can. P2304 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 P2304 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 P2304 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.