P0360 is an ignition coil control circuit code that can make your engine run rough, trigger the check engine light, and leave you wondering what failed. This code points to an electrical problem on one specific coil circuit, not every coil on the engine. In most cases, you’re dealing with a bad coil, wiring issue, or a driver fault inside the ECU. If you catch it early, repairs are usually straightforward and affordable. Ignore it too long, and you risk damaging the catalytic converter and other components.
What Does P0360 Mean?
P0360 is an OBD-II diagnostic trouble code that stands for “Ignition Coil I Primary/Secondary Circuit Malfunction.” The “I” refers to a specific ignition coil (often coil #9 or a designated position depending on the manufacturer). The ECU has detected an abnormal voltage or current in that coil’s control circuit.
In simple terms, the computer is not happy with what it sees on the command or feedback line for that coil. It may be seeing an open circuit, short to power, short to ground, or a coil that’s drawing the wrong amount of current. The result is usually a misfire on that cylinder and a lit check engine light.
Quick Reference
- Code: P0360 – Ignition Coil I Primary/Secondary Circuit Malfunction
- Severity: Moderate to serious (misfire, drivability issues)
- Common causes: Faulty ignition coil, damaged wiring, poor connector, ECU driver fault
- Typical symptoms: Misfire, rough idle, low power, increased fuel use
- Risk: Potential catalytic converter damage if driven misfiring for long
Real-World Example / Field Notes
In the shop, P0360 often shows up on higher-mileage vehicles that have never had the coils or plugs replaced. A common scenario: you come in complaining of a rough idle, flashing check engine light under load, and poor fuel economy. Scan tool shows P0360 and maybe a misfire code for one cylinder. I’ll find a coil boot soaked in oil from a leaking valve cover, or a coil connector with green corrosion inside. Replace the bad coil, clean or repair the connector, clear the code, and the engine smooths right out.
Symptoms of P0360
- Check engine light on: Solid or flashing MIL, often the first thing you notice.
- Rough idle: Engine shakes or feels uneven, especially at stoplights.
- Loss of power: Poor acceleration, sluggish response, especially under load or on hills.
- Engine misfire: Noticeable stumble, hesitation, or “chugging” while driving.
- Increased fuel consumption: You burn more fuel because one cylinder isn’t firing correctly.
- Hard starting: Longer crank time or needing to press the gas to get it going.
- Exhaust odor or popping: Raw fuel smell, occasional popping from the exhaust under misfire.
Common Causes of P0360
Most Common Causes
- Faulty ignition coil: Internal short or open in the coil’s primary or secondary windings is the number one cause. Age, heat, and vibration slowly kill coils.
- Damaged coil connector: Broken lock tabs, loose pins, corrosion, or water intrusion can interrupt the coil control signal.
- Wiring issues: Chafed, pinched, or melted wires between the ignition coil and ECU causing open circuits or shorts to power/ground.
- Worn or incorrect spark plug: Excessive plug gap or wrong plug type can overwork the coil and trigger circuit faults, especially under load.
Less Common Causes
- ECU/PCM driver failure: The internal transistor (driver) that controls that coil can fail, causing no command or improper current flow.
- Aftermarket remote start or alarm wiring: Poorly spliced wiring into ignition circuits can create voltage drops or intermittent opens.
- Moisture intrusion: Water in the plug wells or connectors from washing the engine bay or a leaking cowl can cause shorts.
- Previous repair damage: Bent pins, stretched harnesses, or misrouted wiring from earlier work on valve covers, heads, or intake manifolds.
Diagnosis: Step-by-Step Guide
To properly diagnose P0360, you’ll want at least a basic scan tool, a digital multimeter (DMM), and possibly a test light. An advanced scan tool with Mode $06 data and live misfire counters is even better. If you’re comfortable working around ignition systems and following wiring diagrams, you can do a lot of this yourself.
- Confirm the code and check for companions. Scan the vehicle and note all stored and pending codes. Look for related misfire codes (P030X) or other coil circuit codes that might point to a pattern.
- Inspect the ignition coil and plug area. With the engine off, remove the suspect coil. Look for cracks, burn marks, oil in the plug well, or carbon tracking on the boot or spark plug.
- Swap the coil to another cylinder. Move the suspected coil to a different cylinder and clear the codes. If the misfire or circuit code follows the coil (e.g., now you get a P0361 or misfire on the new cylinder), the coil is bad.
- Check the connector and wiring. Inspect the coil connector for corrosion, loose terminals, or broken locks. Gently tug on each wire. Follow the harness as far as you can, looking for rub-through, melting, or previous repairs.
- Verify power and ground. With the key on, use a multimeter or test light to confirm you have proper battery voltage at the coil power feed and a solid ground (if the coil uses a dedicated ground). Repair any open or shorted circuits.
- Test the control signal. Using a DMM on duty-cycle or an oscilloscope if available, check the control wire from the ECU while the engine is cranking or running. You should see a pulsed signal. No signal may indicate a wiring break or ECU driver failure.
- Check spark plug condition and gap. Remove the spark plug for that cylinder. If it’s worn, fouled, cracked, or has an excessive gap, replace it with the correct plug type and gap per the service manual.
- Use Mode $06 and misfire data. On a capable scan tool, look at Mode $06 misfire counters and coil-related tests. This can confirm which cylinder and coil are acting up under load, even if the misfire isn’t constant.
- Perform a wiggle test. With the engine idling, gently move the harness and connector for that coil. If the engine stumbles or the misfire counter jumps, you’ve likely found an intermittent wiring or connector issue.
- Rule out ECU failure last. If power, ground, wiring continuity, and the coil itself all check out, but the ECU is not driving that coil properly, you may have a failed ECU driver. This usually requires professional testing and programming.
Pro tip: When one coil fails on a high-mileage engine, the others may not be far behind. If your budget allows, replacing coils and plugs as a set on that bank or the whole engine can prevent repeat visits.
Possible Fixes & Repair Costs
Most P0360 fixes are straightforward once you pinpoint the root cause. Typical repairs include replacing a faulty ignition coil, repairing or replacing damaged wiring or connectors, installing new spark plugs, or in rare cases replacing the ECU. At a repair shop, you’re usually looking at about $150–$350 for a single coil and plug replacement, $100–$250 for wiring or connector repairs, and $600–$1,200+ if an ECU replacement and programming is needed. Costs vary by vehicle make, parts quality (OEM vs aftermarket), labor rates in your area, and how difficult the coil or wiring is to access.
Can I Still Drive With P0360?
You can often still drive with P0360, but it’s not a good idea to ignore it. If the misfire is light and intermittent, you may be able to limp the car to a shop without major risk. However, a constant misfire (especially with a flashing check engine light) means unburned fuel is hitting the catalytic converter, which can overheat and fail. Driving in this condition can also cause poor performance, unsafe acceleration, and potential engine damage over time. Treat P0360 as a “fix as soon as possible” situation, not “drive it for months.”
What Happens If You Ignore P0360?
Ignoring P0360 allows a misfire to continue, which can quickly overheat and melt the catalytic converter, foul spark plugs, wash down cylinder walls with fuel, and eventually lead to more expensive repairs. You also risk being stranded if the coil or wiring fails completely.
Related Codes
- P0399 – Ignition Coil “R” Primary/Secondary Circuit
- P0364 – Reserved
- P0363 – Misfire Detected Fueling Disabled
- P0362 – Ignition Coil “L” Primary/Secondary Circuit
- P0361 – Ignition Coil “K” Primary/Secondary Circuit
- P0359 – Ignition Coil “I” Primary/Secondary Circuit
- P0358 – Ignition Coil “H” Primary/Secondary Circuit
- P0357 – Ignition Coil “G” Primary/Secondary Circuit
- P0356 – Ignition Coil “F” Primary/Secondary Circuit
- P0355 – Ignition Coil “E” Primary/Secondary Circuit
Key Takeaways
- P0360 means the ECU has detected an electrical fault in a specific ignition coil’s primary/secondary circuit.
- Most common causes are a bad coil, damaged wiring, or a poor connector; ECU failure is possible but less common.
- Symptoms include check engine light, misfire, rough idle, loss of power, and higher fuel consumption.
- Diagnosis involves visual inspection, coil swapping, checking power/ground, and verifying the control signal.
- Repairs usually range from about $150–$350 for a coil/plug fix to over $600 if the ECU needs replacement.
- Driving with P0360 for long can damage the catalytic converter and lead to more costly repairs.
Vehicles Commonly Affected by P0360
P0360 can show up on almost any OBD-II vehicle with coil-on-plug or coil pack ignition, but it’s more common on certain platforms. You’ll often see it on Ford and Lincoln trucks and SUVs with modular V8 and V10 engines, GM vehicles (Chevrolet, GMC, Cadillac) using coil-on-plug V6 and V8 setups, and various Toyota and Lexus models with individual coil systems. It also appears on Nissan/Infiniti, Chrysler/Dodge/Jeep, Hyundai/Kia, and many European brands that use multiple coils. High mileage, heat, and tight engine bays all increase the odds of this code popping up.
FAQ
Can I clear P0360 and keep driving if the car feels fine?
You can clear the code, but if the underlying issue is still there, P0360 will come back. Even if the car feels okay, an intermittent coil or wiring problem can worsen suddenly and leave you with a hard misfire or no-start. It’s best to diagnose and repair the cause rather than just erasing the code.
Is P0360 always caused by a bad ignition coil?
No. A bad coil is very common, but P0360 can also be triggered by damaged wiring, a loose or corroded connector, or a failing ECU driver. That’s why swapping coils and checking power, ground, and the control signal is important before you throw parts at it.
How do I know which cylinder P0360 is referring to?
The “I” in the code refers to a specific coil position, but the exact mapping depends on your vehicle. Your service manual or a reliable repair database will show which cylinder or coil location corresponds to that label. Often, a companion misfire code (like P030X) will point you to the same cylinder.
Can a bad spark plug cause P0360?
Yes, indirectly. A severely worn or incorrectly gapped spark plug can make the coil work much harder, increasing current and stress on the circuit. Over time, that can cause coil failure or abnormal readings that trigger P0360. That’s why checking and replacing plugs is part of a proper diagnosis.
Do I need to replace all the coils if I get P0360?
You don’t have to replace all the coils, but on high-mileage engines it’s often smart to replace at least the affected coil and plug, and sometimes the whole bank or set if multiple coils are showing issues. This can save you from chasing one failing coil after another over a short period.