P0233
Fix within a few daysIgnition Coil 'C' Secondary Circuit Malfunction, indicating a problem with the high-voltage side of the ignition coil for cylinder #3.
Code P0233 means your engine's cylinder 3 ignition coil has a secondary circuit problem. Common causes: Bad ignition coil (70%), worn spark plug (20%), wiring issues (8%). Drivability: Limit driving, fix within a few days. Repair cost: $35-$120 DIY, $150-$350 professional.
Can I Drive With P0233?
Limit driving, fix within a few days
Essential trips under 10 miles, avoid highways and heavy acceleration to prevent further damage.
Stop driving immediately if: Flashing CEL, loud noises, burning smell, rotten egg smell, significant power loss
Symptoms of P0233
- 1Engine misfire or rough idle
- 2Reduced engine power or hesitation
- 3Engine running poorly
- 4Check Engine Light flashing (indicating an active misfire)
Common Causes of P0233
Parts most likely causing this code, ranked by probability
The ignition coil for cylinder #3 has failed internally, preventing it from generating a strong spark.
70% of P0233 cases are fixed by replacing this part
A worn, fouled, or damaged spark plug in cylinder #3 prevents proper ignition, causing the coil to malfunction or appear faulty.
20% of P0233 cases are fixed by replacing this part
Damaged wires or a corroded/loose connector to the cylinder #3 ignition coil can interrupt the electrical signal.
8% of P0233 cases are fixed by repairing this part
A rare internal fault in the PCM's ignition coil driver circuit for cylinder #3 can cause this code.
2% of P0233 cases are fixed by replacing this part
Check These First (Before Buying Parts)
- Visually inspect the ignition coil and its electrical connector for cylinder #3 for any signs of damage, corrosion, or loose connections.
- Listen for any unusual ticking or sputtering sounds coming from the engine that might indicate a misfire.
How to Diagnose P0233
- 1Visually inspect the ignition coil and spark plug for cylinder #3 for any obvious damage or signs of arcing.
- 2Swap the ignition coil from cylinder #3 with a known good cylinder (e.g., cylinder #1). If the code moves to the new cylinder (e.g., P0231 for cylinder #1), the coil is bad.
- 3If the code does not move, remove and inspect the spark plug for cylinder #3. Look for fouling, damage, or incorrect gap.
- 4Test the resistance of the ignition coil's secondary circuit using a multimeter, comparing it to specifications or a known good coil.
- 5Check the wiring harness and connector to the cylinder #3 ignition coil for continuity, shorts, or corrosion.
- 6If all else checks out, professional diagnosis of the PCM may be necessary.
P0233 on Popular Vehicles
Toyota Camry
2007-2024Camrys are known for ignition coil failures around 100,000-150,000 miles. When replacing a coil, it's smart to inspect the spark plug for that cylinder.
85% fixed by replacing the ignition coil or spark plug
Honda Accord
2003-2024Honda Accords frequently experience ignition coil failures, particularly on higher mileage vehicles. Always check the spark plug for cylinder #3 as well, as a worn plug can stress the coil.
80% fixed by replacing the ignition coil or spark plug
Ford F-150
2004-2024Ford F-150s with coil-on-plug systems are susceptible to ignition coil failures, especially in humid climates or if spark plugs are past their service interval. Ensure the coil boot is properly seated and free of cracks.
88% fixed by replacing the ignition coil or spark plug
Frequently Asked Questions
What does P0233 mean?
P0233 indicates a malfunction in the secondary (high-voltage) circuit of the ignition coil for cylinder #3. This means the coil is not properly generating or delivering the spark needed to ignite the fuel in that cylinder.
Can I drive with P0233?
Limit driving, fix within a few days. A persistent misfire can send unburned fuel into your catalytic converter, causing it to overheat and fail. Drive only for essential, short trips and avoid heavy acceleration.
Will P0233 clear itself?
No, P0233 will not clear itself. This code indicates a hard fault with a component. The underlying issue, such as a bad ignition coil or spark plug, must be repaired for the code to clear. You will need to clear the code with a scan tool after the repair.
How do I fix P0233 myself?
Start by swapping the cylinder #3 ignition coil with a coil from another cylinder. If the code follows the coil, replace the faulty ignition coil. If the code stays on cylinder #3, inspect and replace the spark plug for that cylinder. Check the wiring and connector to the coil for damage.
How much does it cost to fix P0233?
DIY repair costs for P0233 are typically $35-$120 for a new ignition coil and spark plug. Professional repair at a shop usually costs $150-$350, which includes diagnosis, parts, and labor.
P0233 keeps coming back - why?
If P0233 keeps returning, the initial diagnosis was likely incomplete. You might have a wiring issue to the coil, a faulty fuel injector for cylinder #3, or a rare internal PCM problem. Ensure you checked the spark plug, coil, and wiring thoroughly.
Will P0233 fail emissions/smog test?
Yes, P0233 will cause your vehicle to fail an emissions or smog test. A misfire directly impacts exhaust emissions, and the Check Engine Light being on is an automatic failure in most testing jurisdictions.
What's the difference between P0233 and P0303?
P0233 specifically indicates a problem with the secondary circuit of the ignition coil for cylinder #3. P0303 is a general misfire code for cylinder #3, meaning the PCM detected a misfire but doesn't specify the cause. P0233 points directly to the coil as the problem.
P0233 on Ford F-150?
On Ford F-150s, P0233 often points to a failing ignition coil or spark plug on cylinder #3. These trucks use coil-on-plug designs, and coils can fail over time, especially with high mileage. Always check the spark plug condition when replacing a coil.
Questions to Ask Your Mechanic
Did you swap the ignition coil to confirm the fault moved to another cylinder?
Good answer: Yes, we swapped the coil to cylinder #1, and the misfire code followed it to P0231, confirming the coil was bad.
What did you find when you inspected the spark plug for cylinder #3?
Good answer: The spark plug was heavily fouled/worn, which was causing the misfire and stressing the coil. We replaced both the plug and the coil.
Repair Cost Estimate
DIY Repair
Parts only
$35-$120
Shop Repair
Parts + labor
$150-$350
Save $115-$230 by doing it yourself
Difficulty
intermediate
Time
0.5-1.5 hours
Intermediate - requires basic hand tools, a spark plug socket, and an OBD-II scan tool for diagnosis and code clearing.
Cost of Waiting
Continued misfires send unburned fuel into your catalytic converter, causing it to overheat and melt internally. A $35-$120 spark plug and coil job now prevents a $800-$2,500 catalytic converter replacement later.
While You're In There...
You are already accessing the spark plug to get to the coil. Replacing it at the same time is smart, as a worn plug can cause coil failure or be the root cause of the misfire.
Applying dielectric grease to the inside of the new coil boot helps prevent moisture intrusion and ensures a good electrical connection, extending the life of the coil.
Tools You'll Need
- OBD-II scan tool
- Socket wrench set
- Spark plug socket (specific size for your vehicle)
- Extension bar
- Dielectric grease
- Multimeter (for advanced diagnostics)
P0233 is a common ignition system code. Most repairs are straightforward, involving a simple coil or spark plug replacement, and your engine will run smoothly again.
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Your Next Steps
Step 1: Use your OBD-II scan tool to confirm P0233 is the only code. Visually inspect the ignition coil and wiring for cylinder #3.
Step 2: Swap the ignition coil from cylinder #3 with a coil from a different cylinder. Clear the code and drive the vehicle. If the code moves to the new cylinder, replace the faulty ignition coil.
Step 3: If the code remains on cylinder #3 after swapping coils, remove and inspect the spark plug for cylinder #3. Replace it if it's worn, fouled, or damaged. If the issue persists, check the wiring harness for continuity and resistance.