Toyota Yaris Faulty Ignition Coil – How to Diagnose and Fix?

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Toyota Yaris Faulty Ignition Coil – How to Diagnose and Fix?

Hi everyone,

I’ve been noticing some misfiring and rough idling in my Toyota Yaris, and I suspect the ignition coil might be faulty. I’ve read that a bad ignition coil can cause engine sputtering and poor performance.

Has anyone else dealt with a faulty ignition coil in their Yaris? What were the symptoms, and how did you go about diagnosing it? Did you replace the ignition coil yourself, o r did you take it to a mechanic?

Looking forward to your experiences and advice!

Qalb E Momin asked on 28 Jan 2025 14:45:59 pm

1 Answer

23 views |

Car Mechanic Expert - on 28 Jan 2025 14:49:08 pm

A faulty ignition coil could indeed cause misfiring, rough idling, and sputtering in your Toyota Yaris. The ignition coil is responsible for converting electrical power into a spark that ignites the fuel in the engine. When it malfunctions, it can lead to engine performance issues.

Symptoms of a Bad Ignition Coil:

Engine misfiring o r sputtering, especially during acceleration
Rough idling o r shaking at idle
Reduced engine power o r hesitation
Poor fuel efficiency
Check engine light may come on

Diagnosing the Issue:

Check Engine Codes: Using an OBD-II scanner can help identify if theres a misfire code related to the ignition coil.
Visual Inspection: Look for visible damage, cracks, o r corrosion on the ignition coil and wiring.
Swap Test: If you suspect one ignition coil, you can swap it with another cylinder to see if the problem moves, indicating which coil is faulty.

Fixing the Issue:

DIY Replacement: Replacing the ignition coil is often a manageable task for DIYers with basic tools. Youll need to remove the engine cover, disconnect the wiring, and replace the faulty coil.
Professional Help: If youre unsure about replacing it yourself o r the issue involves multiple coils, its best to consult a mechanic.

If your Yaris is experiencing misfiring and rough idling, the ignition coil could very well be the culprit, and replacing it should resolve the issue and restore engine performance.