PRODUCT DETAILS
Genuine Honda Head Gasket - K20 & K24
When you're putting a K-series back together, the head gasket is the one seal you absolutely cannot afford to get wrong. This is the genuine Honda multi-layer steel gasket, the same part that left the factory on the RSX, Civic Si, TSX, Accord, CR-V, and Element. It seals correctly against a properly prepared deck without sealant, without tricks, and without you wondering whether the aftermarket copy on the shelf was worth the savings.
Find Your Gasket First
Five variants here, split by engine and bore size. Match yours before you order, because a head gasket is not a part you want to be wrong about with the engine apart.
| Part Number | Bore | Engine | Found In |
|---|---|---|---|
| 12251-PRB-A01 | 86mm | K20A2 / K20Z1 | 2002-2006 RSX Type-S |
| 12251-PNC-003 | 86mm | K20A3 | 2002-2005 Civic Si, Base RSX |
| 12251-RBC-004 | 86mm | K20Z3 | 2006-2011 Civic Si |
| 12251-PPA-004 | 87mm | K24A1 / K24A4 | 2002-2006 CR-V, 2003-2007 Accord, 2003-2011 Element |
| 12251-RBB-004 | 87mm | K24A2 | 2004-2008 TSX |
Note that the K20 gaskets are 86mm and the K24 gaskets are 87mm, so the bore size follows the engine family. Within each family the part numbers still differ, so go by your specific engine code rather than assuming any K20 gasket fits any K20.
Why MLS Beats A Composite Gasket
Multi-layer steel is what Honda uses on these engines and it's the right technology for the job.
MLS gaskets work by having thin steel layers with embossed beads that spring against the deck and head surfaces. That spring is what maintains sealing pressure through thousands of heat cycles as everything expands and contracts. A composite gasket relies on crushing a softer material into place, which works but doesn't recover the same way and tends to relax over time.
The practical result is a gasket that holds up to sustained high rpm and repeated heat cycling, which is exactly what a K-series does for a living.
Your Deck Surface Matters More Than The Gasket
Worth saying plainly, because this is where head gasket jobs actually fail.
MLS gaskets need a good surface finish to seal properly. They're less forgiving of a rough or damaged deck than a composite gasket, because they're sealing metal against metal rather than filling imperfections with a soft material.
So before this goes on, check your deck and head for flatness with a straightedge, and get them machined if they're out of spec. Clean both surfaces properly, and don't use sealant, MLS gaskets are designed to go on dry and adding sealant can actually prevent them from seating correctly.
A perfect gasket on a warped head leaks. A perfect gasket on a properly prepared surface lasts the life of the engine.
Replace Your Head Bolts
Important, and it's advice that gets ignored regularly. Honda's head bolts on these engines are torque-to-yield, meaning they're designed to stretch permanently during torquing. That stretch is what generates the clamping force.
A stretched bolt has already done that once, and reusing it means you're not getting the clamping load the design calls for. That's how a properly installed gasket ends up leaking anyway.
So plan on new head bolts, or go to a proper stud kit if the engine is being built for more than stock output. Either way, don't put the old ones back in to save a few dollars on a job that costs you a weekend.
An Honest Note On Boost
Being straight with you rather than overselling this. The factory MLS gasket is excellent for its intended purpose, which is a naturally aspirated engine at stock or near-stock cylinder pressure.
If you're building a boosted K-series making serious power, the head gasket is one of the first things that becomes a limiting factor, and that's why aftermarket MLS gaskets in various thicknesses and materials exist. For a stock rebuild, a refresh, or a moderate build, this is the correct part and the sensible choice. For a big-boost build, look at a dedicated performance gasket and proper head studs.
Fitment
2002-2006 Acura RSX Base and Type-S
2002-2005 Honda Civic Si (EP3)
2006-2011 Honda Civic Si
2004-2008 Acura TSX
2003-2007 Honda Accord
2002-2006 Honda CR-V
2003-2011 Honda Element
Select the variant matching your exact engine code.
Who Should Grab One
This is for anyone putting a K-series head back on, whether that's a rebuild, a head refresh, or a repair after a gasket let go. It's the genuine Honda part at a price that makes reaching for a copy hard to justify, given that the labor to install it dwarfs what the gasket costs. Match your engine, prep your surfaces properly, use new bolts, and torque it to spec.
Fits: Honda K20 and K24 engines, see the variant table above. Type: genuine Honda multi-layer steel head gasket. Bore sizes: 86mm (K20) or 87mm (K24). Installation: no sealant required, install dry on a properly prepared surface. Recommended: new head bolts or a stud kit, since factory head bolts are torque-to-yield.