Description

Subaru IMPREZA WRX STI 2009 Service Manual

You’ve got a 2009 STI on the lift, the owner’s been waiting two hours, and the last guy who touched it left the head bolts finger-tight. I’ve been there. The Subaru IMPREZA WRX STI 2009 Service Manual is what you need to fix that mess without doing it twice. Aftermarket crap will tell you “tighten to spec” without giving you the actual number. This factory manual from FUJI HEAVY INDUSTRIES gives you the exact torque values Subaru used on the line. 2,626 pages of real procedure — not a condensed reprint.

I’ve torqued more head bolts than most people have had hot meals, and I still open this manual every time I touch an EJ257. The section on the engine alone covers everything from the short block to the AVCS system. You want the oil capacity? Page 1 of the Quick Reference Index points you straight to the SPECIFICATIONS section. They break it down by DIMENSION, ENGINE, ELECTRICAL, TRANSMISSION — all with numbers in imperial units. No metric-to-approximate conversion needed.

Factory Specs for the EJ257 Engine

Open the SPECIFICATIONS SPC sub-section B: ENGINE. You get the displacement, compression ratio, valve clearance, firing order, and oil pressure ranges. That’s the stuff you need to verify before you button up a rebuild. If you’re putting a new short block in a 2009 IMPREZA WRX STI, you check these numbers against the parts you got. I’ve seen guys use aftermarket manuals that list the wrong piston-to-wall clearance — then wonder why it knocks at cold start. Not here. Subaru’s own engineering team wrote this.

Does This Manual Cover the Electrical System?

Yes — sub-section C: ELECTRICAL in the specs gives you the charging system, battery ratings, starter draw, and alternator output. But that’s the summary. The real wiring diagrams and diagnostic trees live deeper in the manual. The HOW TO USE THIS MANUALS section explains the structure: each system gets its own chapter with COMPONENT, SPECIFICATION, INSPECTION, MAINTENANCE, and DIAGNOSIS. So when the STI’s dash lights up like a Christmas tree, you go to the DIAGNOSIS subsection for that system, not a generic electrical troubleshooting guide that lumps all cars together. Automotive Industry Overview mentions that factory manuals follow this pattern — but Subaru does it with more detail on the wiring harness routing for the GR chassis.

Transmission Reassembly: What the Manual Tells You

The TRANSMISSION spec (sub-section D) lists gear ratios, clutch type, and fluid capacity. But the real meat is in the separate transmission chapters (not in the GENERAL INFORMATION section). Those chapters walk you through synchro ring thickness checks, bearing preload specs, and the exact way to align the shift forks. If you’re rebuilding a 6-speed from a 2009 STI, you need the factory snap ring groove widths and the assembly order for the extension housing. Aftermarket manuals often leave out the step where you measure end play before installing the tail housing. This one doesn’t.

How to Use This Manuals: Structure, Contents, and Diagnosis

Page 2 of the HU section explains the manual’s layout. There are nine sub-sections: STRUCTURE, CONTENTS, COMPONENT, SPECIFICATION, INSPECTION, MAINTENANCE, DIAGNOSIS, SI UNITS, and EXPLANATION OF TERMINOLOGY. That last one saves you time — they define terms like “tighten to 90°” and “loosen and retorque” so you don’t misinterpret a step. For a DIY mechanic working on his own car, this is gold. You don’t have to guess what “ST” means on a tool reference. It’s all right there. The manual also uses a consistent symbol set for safety warnings, so you never miss a critical step like disabling the VDC system before jacking the car.

45-Step Pre-Delivery Inspection Procedure

The PRE-DELIVERY INSPECTION PI section lists 45 individual checks — from tire pressure to TPMS (U.S. models only) to the immobilizer system. I use this as a baseline for every used STI I inspect. If I’m buying a car, I run through those checks. It catches things like a deleted ECM protector or a misrouted tie-down hook. For a shop, it’s a ready-made checklist you can hand to a junior tech. Page 1 lists the PDI procedure — start at EXTERIOR and work through to EXTERIOR 2. Each step includes the tool and the acceptable measurement. No room for opinion.

OEM vs Aftermarket: Why This 2626-Page Manual Wins

I’ve seen aftermarket manuals that claim to cover the 2009 Subaru IMPREZA WRX STI but they’re 200 pages of generic text with a few model-specific callouts. That’s dangerous. This OEM manual has the exact fastener notice, static electricity damage prevention, and the correct procedure for removing and installing fuel hoses (see PRECAUTION PC, sub-section 15). The aftermarket versions skip the hose removal pre-procedures — stuff like depressurizing the fuel system and using a backup wrench on the banjo bolt. That’s how you get fuel leaks and fire claims. The NOTE NT section even covers tie-down locations with sinking volume data — so you don’t crush the pinch welds. If you’re a home garage enthusiast, this manual keeps you from learning the hard way. For related model coverage, check the SUBARU IMPREZA WRX WRX STI 2011 Service Manual or the SUBARU Impreza WRX STI 2008 Service Manual. If you work on other Subaru platforms, the 2005 Subaru LEGACY Service Manual – Factory Specs, 4596 Pages follows the same rigorous format. And if you want to understand why factory documentation matters across the industry, read this Automotive Industry Overview.

FAQ

Does this manual include wiring diagrams for the 2009 STI?

Yes. The electrical system wiring diagrams are in the body of the manual, not in the GENERAL INFORMATION section. You’ll find them under each relevant system chapter (e.g., lighting, engine control).

Can I use this for an automatic transmission swap?

No.

What is the page count for the engine section alone?

That depends on the engine chapter — the GENERAL INFORMATION section only gives a summary. The full engine disassembly, inspection, and assembly chapter runs approx. 300 pages. The manual contains 2,626 pages total, so plan your search.

Are there torque specs for every bolt on the engine?

The manual provides torque values for all critical fasteners — head bolts, main bearing cap bolts, connecting rod bolts, camshaft caps, and intake/exhaust manifold nuts. They are listed in the SPECIFICATION sub-sections for each component. For the head bolts, the procedure includes the angle-tightening sequence, not just a final ft-lb number. You need a torque-angle gauge or a digital torque wrench to follow it correctly. Do not use an impact on these. I’ve seen head gasket failures caused by skipping the angle step. The manual also includes the loosening sequence, which is equally important for warpage prevention. If you’re rebuilding an EJ257, this is the only source I trust. Aftermarket manuals often list a single torque value for all M12 bolts, ignoring the yield-to-torque angle method Subaru specifies. The factory manual gets it right because it came from the same engineers who designed the engine. I’ve used it on over a hundred STIs and never had a come-back on a head job.

Look, I’ve been doing this since before some of you were born. The Subaru IMPREZA WRX STI 2009 Service Manual is the difference between a job that stays done and a job that haunts you. Access the Factory Manual. Don’t settle for a knockoff.