Most parts listings throw a wall of numbers at you and hope nobody asks questions. Resistance values, voltage ranges, connector layouts — they sit in fine print while the product photos and the price tag do all the selling. That’s backwards when you’re shopping for an ignition coil, because a coil is nothing more than a precision transformer, and transformers live or die by their specifications. The OSRAM OS1056, built to replace GM’s 24100593 coil on Buick applications, happens to be a perfect excuse to walk through what those numbers mean once the part is actually bolted to your valve cover.
Why the Spec Sheet Deserves More Attention Than the Box Art
Aftermarket buyers tend to shop by brand recognition and price, and honestly, that instinct isn’t crazy — until it fails. Two coils can look identical from the outside: same plastic housing, same boot shape, same connector. Inside, though, the differences are enormous. Wire gauge in the windings, insulation quality, the epoxy used to pot the assembly, even the magnetic core material — every one of those choices changes how much voltage the coil delivers and how long it survives underhood.
A coil has one job: convert the vehicle’s 12-volt supply into a pulse of 30,000-plus volts strong enough to jump the spark plug gap under compression. When a coil can’t quite do that anymore, the engine doesn’t always throw a dramatic no-start. More often you get the slow-motion failures techs see daily — a rough idle that comes and goes, hesitation when accelerating onto a highway ramp, a check engine light logging P0300 through P0304 misfire codes. The spec sheet is where you catch those problems before they happen, not after.
The OS1056 Spec Sheet, Line by Line
Here’s the quick-reference version, followed by the details that actually matter in a service bay. Values shown are typical for this class of GM coil-on-plug unit; treat them as the neighborhood, not gospel down to the decimal.
| Spec | Typical Value (This Coil Class) | What It Means in Practice |
|---|---|---|
| OE cross-reference | GM 24100593 | Direct bolt-in replacement, no harness modifications |
| Operating voltage | 9–16V on a 12V system | Fires reliably through cranking sag and alternator spikes |
| Secondary output | ~30–40 kV | Jumps a worn plug gap under heavy load |
| Primary resistance | ~0.3–1.0 Ω | Fast dwell times without cooking the driver circuit |
| Secondary resistance | ~5–10 kΩ | Consistent spark energy across all cylinders |
| Connector | OEM-style sealed multi-pin | Plug-and-play install, no cut-and-splice wiring |
| Construction | Epoxy-potted windings | Resists moisture, oil mist, and vibration |
Secondary Voltage Output: The Number That Starts the Engine
Output voltage gets all the marketing attention, and for good reason. A healthy coil needs serious reserve voltage — not just enough to jump a fresh 0.04-inch plug gap in open air, but enough to force a spark through a compressed air-fuel mixture with a plug that’s seen 60,000 miles. As plugs wear, the gap widens and the voltage demand climbs. A marginal coil that idles fine will start breaking down exactly when the engine is under load: passing gear, towing, climbing a grade with the AC blasting.
That’s why the 30–40 kV range matters. It’s headroom. When a customer complains the car “runs fine cold but stumbles when hot,” a coil with thin voltage reserve is suspect number one.
Primary Resistance: Small Ohms, Big Consequences
Primary resistance sounds boring until you understand what it controls. The low-resistance primary winding charges up during the dwell period — the few milliseconds the coil saturates before the ECM cuts the current and the spark fires. Too much resistance and the coil can’t fully charge between firing events, especially at high RPM. Too little, and the current draw can stress or damage the ignition driver inside the ECM, which turns a $60 coil repair into a four-figure module replacement.
This is also why resistance mismatches trigger trouble codes. If one coil on a four-cylinder reads noticeably different from its siblings, the ECM sees inconsistent feedback and sets a P0351–P0354 circuit code alongside any misfire codes. Techs who test coils with an ohmmeter already know this; owners buying online should know that matching OE resistance values is what keeps those codes away.
Connector and Terminal Design: Where Cheap Coils Go to Die
Coils aren’t usually published with IP ratings the way sensors and cameras are, but the concept translates directly — it’s just called potting and sealing instead. Underhood temperatures swing from freezing mornings to 200°F+ soak conditions, and every cycle works terminals loose and cracks cheap housings. A corroded or loose connector terminal mimics a dead coil perfectly, which is why experienced techs wiggle-test connectors before condemning the part.
The OS1056 uses an OEM-pattern sealed connector, and that’s not a trivial detail. It means the mating terminals carry proper spring tension, the seal blocks water intrusion during car washes and rain-soaked commutes, and installation is genuinely plug-and-play. Avoid any coil that arrives requiring you to splice a pigtail — every splice in a high-voltage ignition circuit is a future misfire waiting for a humid day.
Shop tip: Before installing any new coil, apply a dab of dielectric grease to the connector terminals and inspect the spark plug boot for nicks. Most “defective new coil” returns I’ve seen were actually damaged boots or contaminated terminals.
Potting and Thermal Construction
Cut open a failed budget coil and you’ll often find voids in the epoxy — air pockets where moisture creeps in, arcs internally, and carbon-tracks the housing. Quality potting fills every cavity around the windings, which is why it’s worth asking about construction rather than assuming all coils are equal. OSRAM’s background is in automotive electrical components rather than engine internals, and that engineering culture shows up in details like consistent potting and stable resistance values across production runs.
Fitment and Real-World Performance
The listing currently confirms one Buick application under OE number 24100593, and I’d treat that single-application figure as a feature rather than a limitation. GM reuses and revises part numbers constantly across platforms, so a coil claiming to fit “everything” is usually a red flag, not a bonus. Match the OE number, confirm with your VIN through the fitment checker, and you’re done guessing.
Installation itself is straightforward on coil-on-plug engines — one bolt, one connector, done in minutes per cylinder. What owners notice afterward tends to follow a pattern: the cold-start stumble disappears first, then the idle smooths out, and fuel economy ticks back toward normal if a lazy coil had been quietly dumping unburned fuel toward the catalytic converter. On that last point, timing matters. A flashing check engine light means active catalyst-damaging misfires; replacing a failing coil promptly is cheaper than a converter.
One honest caveat: no replacement coil makes more power than a healthy original. What a properly specced unit like this restores is consistency — the same spark event, cylinder after cylinder, mile after mile. That’s the whole game.
Verdict: Who Should Buy, Who Should Skip
Buy the OS1056 if your Buick’s OE number matches 24100593 and you want an OE-equivalent replacement without dealer pricing. It suits DIY owners comfortable with basic hand tools and independent shops that stock a reliable coil rather than gambling on the cheapest shelf unit. The spec profile — proper voltage reserve, matched resistance, sealed OEM connector, solid potting — checks every box that separates a lasting repair from a comeback job.
Skip it if your vehicle calls for a different OE number, or if you’re building a tuned engine that needs upgraded performance coils with higher energy output. Stock replacement is the right answer for a stock car.
If your scan tool keeps pointing at a specific cylinder and the old coil fails an ohmmeter check against spec, the OS1056 | OSRAM Ignition Coil | Fits Buick | OE# 24100593 is the straightforward path back to a smooth-running engine — verify your fitment, order it, and keep a spare on the shelf. At the price longweiparts.com lists it for, stocking one ahead of failure costs less than one tow.
Recommended Part: OS1056 – OE-quality aftermarket part, ready to ship.
