P2303Ignition System
Ignition Coil B Primary Control Circuit Low
P2303 means the ECM detected low voltage on the primary control circuit for ignition coil B. The cylinder served by coil B is likely misfiring.
🚗 Not recommended. The affected cylinder is misfiring and can damage the catalytic converter.
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🎯 Top Causes, Ranked by Likelihood
#1Failed ignition coil (cylinder B)$30-$120
Internal primary winding fault in the coil-on-plug unit.
#2Wiring or connector fault at the coil$40-$250
Corroded connector, chafed wire, or poor ground.
#3ECM driver circuit fault$200-$900
Rare failure of the coil driver inside the ECM.
🩺 Common Symptoms
- Single cylinder misfire
- Rough idle and shaking
- Check engine light, sometimes flashing
- Loss of power
- Increased fuel use
💰 Repair Cost: DIY vs Shop
📋 Free OBD2 Code Cheat Sheet
The 50 most common codes with likely cause and DIY fix cost. Sent once, no spam.
🔧 How to Diagnose P2303
1Determine which cylinder coil B feeds on your engine
2Swap the coil with an adjacent cylinder to see if the code follows
3Inspect the coil connector and wiring
4Replace the coil if the fault follows it
❓ Frequently Asked Questions
Can I drive with P2303?
Not for long. A misfiring cylinder can overheat and destroy the catalytic converter. Stop soon if the light is flashing.
How much to fix P2303?
A single coil runs $30-$150 DIY, or $120-$400 at a shop.
Will P2303 come with a misfire code?
Often yes. You may see a matching misfire code like P0302 for the same cylinder.
🔗 Related Codes
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