Is there a code for ignition coil?
Yes. In modern vehicles, ignition coil faults are identified by diagnostic trouble codes (DTCs) within the OBD-II framework, most commonly P0350 through P0356 for ignition coil primary/secondary circuit faults, with variations depending on engine layout and manufacturer.
Understanding ignition coil codes in OBD-II
Car diagnostics rely on standardized OBD-II codes to flag problems in the ignition system. The most familiar range for ignition coils covers multiple coils in the engine—A through F in a six-coil setup—each able to trigger a separate code if its circuit malfunctions. Some engines with more cylinders or different coil configurations may use additional codes or manufacturer-specific naming.
Standard ignition coil codes (P0350–P0356) and beyond
Common codes you may encounter on a scan tool relate to individual coils or coil circuits. The list below reflects typical patterns used by many automakers; exact codes can vary by brand and model:
- P0350 Ignition Coil A Primary/Secondary Circuit Malfunction
- P0351 Ignition Coil A Primary Circuit Malfunction
- P0352 Ignition Coil B Primary Circuit Malfunction
- P0353 Ignition Coil C Primary Circuit Malfunction
- P0354 Ignition Coil D Primary Circuit Malfunction
- P0355 Ignition Coil E Primary Circuit Malfunction
- P0356 Ignition Coil F Primary Circuit Malfunction
Note: Some engines or manufacturers may extend this pattern to coils G, H, and beyond (for example P0357, P0358, etc.) or use different prefixes. Always cross-check with the vehicle’s service information or a trusted OEM diagnostic reference for your specific model.
Concluding paragraph: The presence of these codes points toward a coil or its driving circuit as the likely culprit, but they do not always pinpoint the exact failed component. Diagnostic work typically progresses from code interpretation to electrical testing and, if needed, component testing or swapping.
Different ways ignition coils are identified and replaced
Beyond the DTCs, technicians must identify the physical coil configuration and part numbers to source the correct replacement. The coil’s format and labeling determine compatibility with the engine.
- Coil type: Coil-on-plug (COP) versus traditional coil packs. COP assemblies mount directly on each spark plug; coil packs group multiple coils in a single housing.
- Part identification on the coil: Each coil carries a manufacturer part number and stamping that map to specific engines and VINs.
- Source of parts: Replacement parts come from OEMs or aftermarket brands (Bosch, Denso, NGK, Delphi, etc.).
- Configuration considerations: Cylinder count, firing order, and engine design determine which coil(s) need replacement.
Concluding paragraph: Correctly identifying the coil type and the exact part number is essential to ensure compatibility, performance, and warranty coverage. When in doubt, verify with the vehicle’s VIN, engine code, and official service information.
What to do if you see ignition coil codes
If you encounter P0350–P0356 or related codes, follow these steps to diagnose and confirm the fault:
- Run a full OBD-II scan with a reliable reader to confirm the codes and retrieve freeze-frame data.
- Inspect wiring harnesses and connectors to each coil for damage, corrosion, or looseness.
- Test coil resistance (primary and secondary windings) and compare against manufacturer specifications.
- If available, perform a controlled swap: replace or swap a suspected coil with a known-good one to see whether the misfire moves to the other cylinder.
- Check for related codes (misfire, crank/cam sensors, fuel delivery, PCM health) that could influence coil performance.
Concluding paragraph: A methodical approach—confirming the code, verifying electrical integrity, and ruling out wiring or control module issues—helps determine whether the ignition coil itself is at fault or if the problem lies elsewhere in the ignition circuit.
Summary
In routine diagnostics, ignition coil faults are most commonly reported as OBD-II codes in the P0350–P0356 range, corresponding to coil A through F circuits, with variations across engine designs and manufacturers. Diagnosing the fault requires reading the codes, inspecting wiring, testing coil resistance, and considering coil type and part numbers for replacement. When in doubt, consult OEM service information or a qualified technician to ensure accurate identification and proper repair.
Will a bad ignition coil throw a code?
Yes, a bad ignition coil will typically throw a check engine light and set a diagnostic trouble code (DTC). The most common codes are P0300-P0312 (random or specific cylinder misfire) or a specific ignition coil circuit code, such as P0351 for cylinder 1.
You can watch this video to learn about the symptoms of a bad ignition coil: 56sFixITYouTube · Oct 3, 2024
How it happens
- A faulty ignition coil fails to send enough voltage to the spark plug, preventing a spark.
- The engine's computer (ECM) detects the misfire in that cylinder because there's no combustion.
- The ECM then turns on the check engine light and records a trouble code.
Common trouble codes
- Misfire codes: A code like P0301 indicates a misfire in cylinder 1, P0302 in cylinder 2, and so on.
- Ignition coil circuit codes: A code like P0351 indicates a problem with the primary circuit for the ignition coil in cylinder 1.
- Note: Some failing coils may only trigger a misfire code, not an explicit "coil circuit" code, and this can sometimes depend on how the ECM is designed to test the coil.
How to tell if a coil needs replacing?
You can tell a coil needs replacing by observing symptoms like poor performance, such as a burnt taste from a vape or engine misfires in a car. Other signs include a decrease in vapor or power, an illuminated "check engine" light, leaking, or unusual sounds like gurgling or backfiring. A visual inspection for physical damage like cracks, and using a diagnostic scanner to check for specific codes can also confirm a bad coil.
For a vehicle ignition coil
- Check Engine Light: An illuminated light on the dashboard is a common indicator of an ignition system issue.
- Engine Misfires: You may feel the engine shudder, jerk, or run unevenly, especially during acceleration.
- Rough Idle: The engine may shake or vibrate noticeably when the car is stopped.
- Difficulty Starting: The engine may take longer to crank before starting or might not start at all.
- Reduced Power: You might notice a loss of power when accelerating or a general sluggishness.
- Poor Fuel Economy: The engine may burn fuel inefficiently, leading to worse gas mileage.
- Backfiring: A sudden backfire (a loud pop) can occur if unburnt fuel ignites in the exhaust system.
- Visual Damage: Look for physical damage like cracks in the coil's housing or oily residue around it.
- Diagnostic Codes: An OBD-II scanner can read trouble codes (like P0300) that point to a specific cylinder misfire.
For a vape coil
- Burnt Taste: This is the most common sign, as the cotton wicks and coil element wear out over time.
- Diminished Flavor: Your e-liquid may not taste as good or the flavor profile becomes weaker.
- Reduced Vapor: Your device produces less vapor than it used to.
- Gurgling Sounds: A hollow bubbling sound can indicate the coil is having trouble and needs replacing.
- Leaking: A worn-out coil can cause the e-liquid to leak from the device.
- Darker E-juice: The color of your e-liquid might darken prematurely.
- Airflow Clogging: You may notice the airflow feels restricted or clogged.
How serious is the P0354 code?
It's best to avoid driving a vehicle with this trouble code. The vehicle likely won't be producing its full power, and continued operation when down a cylinder can cause an imbalance that may lead to other problems. It's best to take the vehicle to get checked out as soon as you detect the P0354 error code.
What is the fault code for the ignition coil?
P0351
The most common DTC fault code when using an OBD II car diagnostic tool is P0351 (Ignition Coil 1 Primary/Secondary Circuit Malfunction).
