How many ohms should a coil pack have?
There is no single ohm value that fits all coil packs; typical ranges depend on design. In most modern systems, the primary winding reads roughly 0.5 to 1.5 ohms and the secondary winding about 6,000 to 15,000 ohms.
Beyond the quick answer, the question hinges on the coil type (coil-on-plug versus multi-coil packs), engine design, and the intended performance. This explainer outlines what those numbers mean, how to verify them, and what to do if readings don’t match factory specs.
Understanding coil-pack resistance
Resistance readings come from measuring the windings with the ignition system isolated. Primary (low-voltage) and secondary (high-voltage) windings are designed to deliver the right current and spark energy. Because coil designs vary by manufacturer and engine, the exact targets are specified by the OEM or coil maker.
Typical ranges by winding type
Before listing the common ranges, note that exact targets come from OEM specs. The ranges below reflect what you might expect on many modern engines.
- Primary winding (low-voltage side): approximately 0.5 to 1.5 ohms. This winding connects to the ignition coil driver and battery through the control module.
- Secondary winding (high-voltage side, to the spark plug): typically about 6,000 to 15,000 ohms. This winding determines spark energy and arc formation.
Because coil packs vary widely, always compare measurements to the official specification for your engine or coil model. If readings fall outside the stated tolerance, the coil pack or its circuitry may be faulty.
How to test coil-pack resistance
Performing a resistance check requires care and the right technique. Below are the general steps used by technicians to verify winding continuity and resistance.
- Safety first: disconnect the battery and remove the spark plug cap or coil-on-plug boot if testing secondary resistance. Allow the engine to cool.
- Identify the windings: locate the primary terminals (low-voltage side) and the secondary terminal (the spark plug connection) on the coil pack.
- Measure primary resistance: set the multimeter to the ohms range and place probes on the two primary terminals. Record the value.
- Measure secondary resistance: place one probe on the secondary terminal (spark plug boot connection) and the other probe on the coil’s ground or the corresponding primary terminal as specified by the service manual.
- Compare values: match both primary and secondary readings against the manufacturer’s spec for your exact coil or engine. Note tolerances (often ±5–20% depending on the coil).
- Act on the results: if the readings are out of tolerance, replace the coil pack or module. Re-test after replacement to confirm.
Note: Some coil systems are sealed or non-resistance-measurable in the field; in those cases, replacement based on performance symptoms (failure to start, misfire codes, rough idle) may be the practical path while using factory specs for comparison where available.
Summary
In short, there is no one universal ohm value for a coil pack. Expect primary windings to sit roughly between 0.5 and 1.5 ohms and secondary windings between about 6,000 and 15,000 ohms on many modern designs. Always verify against the exact specs for your engine and coil type, and use a multimeter to test both windings carefully. If readings fall outside the recommended range or performance deteriorates, replacement is typically warranted.
