Ignition Coil "B" Primary Control Circuit High
P2304 indicates the ignition coil B primary control circuit voltage is abnormally high, meaning the PCM detected excessive voltage when trying to command the coil. This prevents proper ignition spark generation for one or more cylinders, causing misfires and reduced engine performance.
What You Might Notice
- Engine misfire or rough idle
- Diminished engine performance and acceleration
- Reduced fuel efficiency
- Check engine light illuminated
- Possible fuel injector disabling for affected cylinder
Most Common Causes
- 1
Faulty ignition coil
The ignition coil B may have an internal short or failure causing excessive voltage in the primary control circuit. This is the most common cause of this code.
- 2
Wiring harness damage or short
Damaged, pinched, or shorted wiring in the ignition coil B control circuit can create a high voltage condition that the PCM detects as a fault.
- 3
PCM or ignition driver module failure
A faulty powertrain control module or ignition control driver circuit may not properly regulate voltage to the ignition coil, resulting in high circuit voltage.
- 4
Corroded or loose electrical connectors
Poor connections at the ignition coil connector or PCM connector can cause voltage irregularities and trigger the control circuit high error.
How to Diagnose It
- 1
Check Faulty ignition coil — The ignition coil B may have an internal short or failure causing excessive voltage in the primary control circuit. This is the most common cause of this code.
- 2
Check Wiring harness damage or short — Damaged, pinched, or shorted wiring in the ignition coil B control circuit can create a high voltage condition that the PCM detects as a fault.
- 3
Check PCM or ignition driver module failure — A faulty powertrain control module or ignition control driver circuit may not properly regulate voltage to the ignition coil, resulting in high circuit voltage.
- 4
Check Corroded or loose electrical connectors — Poor connections at the ignition coil connector or PCM connector can cause voltage irregularities and trigger the control circuit high error.
How to Fix It
- 1
Replace ignition coil B
Remove the faulty ignition coil B and install a new OEM or quality aftermarket replacement. Verify the new coil resolves the code before reassembling.
- 2
Inspect and repair wiring harness
Visually inspect the ignition coil B wiring harness for damage, corrosion, or shorts. Repair or replace damaged sections and ensure proper connections at both ends.
- 3
Clean and reseat electrical connectors
Disconnect the ignition coil B connector and PCM connectors, clean oxidation with a wire brush, apply dielectric grease, and firmly reseat all connections.
- 4
Test and replace PCM if needed
If coil, wiring, and connectors test good, have the PCM or ignition control driver module tested by a professional technician. Replace if defective.
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