Spark Plug 4955850 4937472 5473010 | Model-Matched for Cummins Engine

Verified Cross-Reference — Thread reach, seat angle, and electrode gap confirmed against Cummins gas engine serial variants before dispatch.

Technical Specifications

Application Suitability

Why the Same Part Number Ships in Three Variants Across Cummins Gas Platforms

Cross-reference tables copied between sellers frequently carry errors forward, sending the wrong plug to a machine that is already down.

When a buyer submits 4955850, 4937472, or 5473010, the first question is never "do you have it in stock" — it is "does this actually fit my specific CM code." I have seen plugs that share a base number but differ in reach by a fraction of a millimetre get forced into cylinder heads, causing tapered seat deformation or, worse, porcelain insulator fracture under combustion pressure [NEED_CITE: Cummins gas engine spark plug variant differences across CM codes]. A Spark Plug for Cummins ISB5.9G QSL9 L9N cross reference must account for serial-range changes, not just the marketing model name. The ISB5.9G CM2180 and ISC8.3 G CM2180 C101, for instance, share a platform designation but can differ in head casting revision, which changes the effective reach requirement.

Mapping Reference Numbers to Engine Build Codes

The three interchange reference numbers — 4955850 (cross-reference only), 4937472 (cross-reference only), and 5473010 (cross-reference only) — do not apply uniformly across every Cummins gas engine in the field. Each number corresponds to a particular production window and CM controller revision. The Spark Plug for Cummins ISB5.9G QSL9 L9N cross reference exercise requires pulling the engine serial number, matching it to the CM code on the dataplate, and then confirming which of the three numbers the factory build sheet specifies. Skipping this step is how fleets end up with a carton of plugs that physically thread in but leave the electrode positioned too deep or too shallow in the combustion chamber, triggering misfire under load.

Thread, Seat, and Reach: The Three Dimensions That Cannot Be Approximated

The 14 mm × 1.25 mm thread pitch, 19° tapered seat, and 19.5 mm reach are not suggestions — they are the dimensional contract between the plug shell and the cylinder head [NEED_CITE: SAE J1330 spark plug dimensional standards for heavy-duty gas engines]. A plug with the correct thread but a 16 mm reach instead of 19.5 mm will leave the electrode recessed inside the plug well, producing a weak spark that fails to ignite lean-burn natural gas mixtures reliably. Conversely, excessive reach exposes shell threads to combustion temperatures, accelerating carbon lock and making removal at the next service interval a cylinder-head repair event. The 16 mm hex must also match the socket inventory on site; a mismatch here means the maintenance crew cannot torque the plug without improvising, which introduces angular loading and cracked ceramic risk.

What Happens When the Cross-Reference Is Wrong

A mismatched spark plug does not always fail dramatically. More often, it produces a subtle misfire that the engine controller compensates for by enriching the mixture, increasing fuel consumption and accelerating catalyst degradation over hundreds of operating hours [NEED_CITE: lean-burn gas engine misfire effects on aftertreatment systems]. In landfill compactors running on biogas — where fuel composition already fluctuates — a plug that sits slightly too deep in the chamber will foul faster, pulling the machine off the working face for unplanned servicing. For municipal refuse trucks on CNG routes, the consequence is a derated engine that cannot maintain highway speed on grade, forcing fleet dispatch to reassign routes. These are not warranty claims; they are operational losses that never appear on a parts invoice.

Why Procurement Verification Starts with the Dataplate, Not the Catalogue

When a nameplate is worn, painted over, or replaced during a prior overhaul, the engine model alone — say, QSL9 G — is not enough to guarantee the correct plug. The CM558 controller revision, the L124B build variant, and even the production month can shift which reference number applies. Our technical team asks for the serial number, a photograph of any legible markings on the old plug, and the machine model. We then cross-verify against the three reference numbers and confirm reach, seat angle, and hex size before releasing a sample. That sample goes into the actual cylinder head for a hand-thread fitment check before the buyer commits to a bulk order for the entire fleet.

Why Source the Spark Plug for Cummins ISB5.9G QSL9 L9N Cross Reference Here

Production on selected plug lines runs in our own facility alongside qualified sourced supply, both carrying identical QC and warranty terms — one account, one warranty, no finger-pointing between suppliers. Eight product categories mean a complete ignition service kit — plugs, ignition coils, wiring harnesses, filters — ships as a single consignment rather than three separate deliveries with mismatched lead times. Minimum order is one piece, so a single emergency replacement for a downed machine does not require meeting a bulk threshold. Our Guangzhou warehouse holds stock on fast-failure ignition items for same-week dispatch. Part identification works from a part number, a machine model, a photograph, or a nameplate image — whichever the buyer has available. Cross-reference verification covers superseded and alternate numbers across the three reference designations.

Documentation & Verification

• Commercial invoice and packing list itemising each plug by reference number and engine fitment
• Compatibility and cross-reference sheet mapping 4955850, 4937472, and 5473010 to specific CM codes (reference only)
• Dimensional inspection record confirming thread pitch, reach, hex size, and seat angle before dispatch
• Warranty terms covering manufacturing defects for 3–12 months depending on application severity
• Packing photographs showing individual plug condition and protective packaging prior to crate sealing
• HS code and customs documentation support for international gas-engine parts shipments

Fitment Check Before Installation

• Hand-thread each Spark Plug into the cylinder head before applying torque to confirm 14 mm × 1.25 mm engagement
• Verify 19° tapered seat makes full contact without forcing — resistance before seating indicates debris or wrong seat type
• Compare reach of new plug against removed unit; 19.5 mm must match to avoid electrode recession or thread exposure
• Check 16 mm hex fits available torque socket without wobble; angular misalignment cracks alumina insulator under load
• Confirm spark gap within ±0.05 mm tolerance using a wire gauge, not a coin-style feeler gauge
• If fitment fails on any dimension, stop installation and submit photographs for cross-reference re-verification

Request a Fitment Verification Before You Commit

Send the engine serial number, CM code from the dataplate, and a photograph of the existing plug — including any legible markings on the shell or ceramic. We will return a confirmed cross-reference match, dimensional verification, and a sample arrangement so your team can validate fitment on the actual machine before committing to fleet-scale quantities.

Frequently Asked Questions

Q: How do I confirm which of the three reference numbers fits my specific engine CM code? A: Provide the full engine serial number and the CM code printed on the dataplate (e.g., CM2180, CM558, CM2380 L124B). We cross-verify against all three reference numbers — 4955850, 4937472, and 5473010 — and return the exact match for your build. If the dataplate is illegible, a photograph of the old plug and the machine model is usually sufficient for identification.

Q: My old spark plug number is superseded — does the replacement fit the same cylinder head? A: Superseded numbers often reflect material or electrode design changes while retaining the same shell dimensions. We verify that the replacement maintains the 14 mm × 1.25 mm thread, 19.5 mm reach, and 19° tapered seat of the original. If the cylinder head was modified during a prior overhaul, we may request a measurement confirmation before shipping.

Q: I only have the engine model (e.g., QSL9 G), not the part number — can you identify the correct plug? A: Yes, but we will need additional detail beyond the model name. The QSL9 G CM558, for example, may use a different reference number than an earlier QSL9 build. Provide the serial number or a dataplate photograph. If neither is available, a clear image of the existing plug's shell markings often allows identification through cross-reference.

Q: Can I get a sample to verify fitment before ordering for the whole fleet? A: Sample supply is available specifically for this purpose. We ship one piece so your maintenance team can hand-thread it into the cylinder head, confirm seat contact, reach alignment, and hex fitment. Once fitment is validated physically, bulk quantities ship against the confirmed specification with no guesswork remaining.

Q: Why do different sellers list different compatibility for the same base part number? A: Cross-reference tables are frequently copied between aftermarket listings without verification against specific CM codes and serial ranges. A plug that fits an ISB5.9G CM2180 may not suit an ISC8.3 G CM2180 C101 despite sharing a base platform. We verify each listing against the engine build sheet rather than relying on aggregated tables that carry forward errors.