Ignition Coil B Primary Control Circuit High
The P2303 code means the vehicle's onboard diagnostic system has detected: Ignition Coil B Primary Control Circuit High. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $50 - $300 (parts and labor)
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Common Symptoms
- Misfire on cylinder associated with coil B
- Check Engine Light on or flashing
- Engine running rough
- Lack of power on acceleration
- Increased emissions output
Probable Causes (Ranked by Likelihood)
- Short circuit in coil B wiring Very High
- Failed ignition coil B (internal short) High
- Coil B connector pins shorted together Moderate
- ECM coil driver output shorted Low
Step-by-Step Diagnostic Procedure
-
Swap coil B to another cylinder to confirm the fault
-
Check coil B connector for melted or bent pins
-
Measure coil B primary and secondary resistance
-
Inspect wiring for heat damage near the exhaust manifold
-
Check for carbon tracking on the coil or spark plug boot
Frequently Asked Questions
Can I drive with code P2303?
Short distances only. Misfiring causes unburned fuel to enter the catalytic converter, which can cause overheating and expensive damage.
What causes P2303?
Usually a failed ignition coil or wiring damage from exhaust heat. Coils near the exhaust manifold are more susceptible to heat-related failure.
Is P2303 expensive to fix?
Usually $50 to $300. Ignition coil replacement is straightforward. Replace the spark plug at the same time for best results.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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