Nissens Automotive — ignition coil technical focus
25 February 2026 
The introduction of ignition coils to the Nissens Automotive (Nissens) engine efficiency portfolio is a significant, strategic expansion that adds further depth to the aftermarket specialists’ growing product offering.
What this means to independent workshops and the technicians responsible for servicing and repairing vehicles is the reassurance that the same level of premium quality products and comprehensive technical support that is standard with its existing products, will be carried across to this system critical component, which is essential for maintaining engine performance and emissions control.
To learn more, visit www.nissens.com/ignition-coil
Common symptoms of failure
The ignition system and the coil issues directly affect the engine’s operation. Besides noticeably affecting the overall drivability, ignition coil failures can ultimately result in severe damage to the engine and its equipment. Recognising the symptoms of a coil problem early is key to preventing these issues. A faulty or non-performing ignition coil is generally easy to recognise from a range of symptoms:
- Check engine light (CEL): Often the first indicator. Diagnostic trouble codes such as P030X (misfire) or P035X (coil circuit fault) point to specific cylinders or coils;
- Hard starting or no start: a weak or failed coil can cause extended cranking or prevent the engine from starting, especially in cold conditions;
- Engine misfires and rough idle: misfiring cylinders result in rough idling, shuddering and poor acceleration;
- Backfiring: unburned fuel igniting in the exhaust system produces loud pops and can damage the catalytic converter;
- Engine stalling: intermittent coil failure may cause the engine to stall unexpectedly, posing safety risks;
- Loss of power and poor fuel economy: inefficient combustion due to weak spark leads to reduced power output and increased fuel consumption.
What can break: common failures
Ignition coils are subject to various stress factors that can lead to failure. Understanding these helps in accurate diagnosis and prevention:
- Internal coil damage: open or shorted windings disrupt the coil’s ability to generate a spark. Overheating and age are common contributors;
- Insulation breakdown and arcing: cracks in the coil’s resin casing or carbon tracking allow voltage to escape, causing misfires and visible sparks;
- Connector and wiring issues: loose, corroded, or damaged connectors can mimic coil failure by interrupting power or signal flow;
- Multiple coil failures: often linked to underlying issues such as excessive spark plug gaps, lean fuel mixtures, or faulty ECU drivers. These conditions overstrain coils and lead to repeated failures.
Review of internal structural failures
Physical or electrical faults within the coil’s components:
- Internal short circuit – current bypasses windings, weakening spark output; caused by insulation breakdown or overheating;
- Open circuit in windings – broken wire prevents voltage generation, resulting in no spark and misfire or no start;
- Carbon tracking or arcing – spark diverts from plug path due to surface burns or cracks; often triggered by moisture or contamination;
- Cracked housing or boot – allows voltage leakage or environmental intrusion, leading to misfires and coil degradation;
- Epoxy insulation failure – breakdown of internal insulation material causes overheating and electrical instability;
- Connector damage or corrosion – interrupts electrical contact, causing intermittent coil operation or complete failure.
Review of incorrect performance parameters
Functional deviations of the coil
- Incorrect coil impedance – disrupts voltage buildup, causing weak spark and misfires; often due to winding damage;
- Incorrect charge current – insufficient magnetic field buildup leads to low spark energy and poor combustion;
- Incorrect discharge timing – spark occurs too early or late, causing misfires, knocking, or rough running;
- Voltage leakage – high voltage output escapes before reaching the plug, reducing spark strength and efficiency;
- Overheating under load – coil fails to maintain output during high demand, leading to misfires or stalling;
- Inconsistent dwell time – coil charging duration varies due to ECU or driver faults, affecting spark reliability.
Diagnostic methods and tips
Effective diagnosis of ignition coil issues involves a combination of visual inspection, electronic testing and practical techniques:
- OBD-II scan: retrieve misfire (P030X) and coil circuit (P035X) codes to identify affected cylinders;
- Visual inspection: check for cracks, carbon tracking, oil contamination and connector corrosion;
- Spark test: use an inline spark tester to verify spark strength and consistency.
- Coil swap test: move suspect coil to another cylinder and observe if the misfire follows.
- Resistance measurement: use a multimeter to check coil windings against the manufacturer’s specifications;
- Replace all coils if one fails: in high mileage engines, a single coil failure often signals that others are nearing the end of their life. Replacing all the coils ensures balanced performance and avoids repeated labour costs.