Brands
Showing 12 of 588
HKS
HKS SUPER SQV 4 RETURN KIT PLUS GXPA16
$748.00
HKS
HKS SSQV IV + Return Kit GR SUPRA (DB42/DB02) for Normal Box
$1,430.00
HKS
HKS SSQV IV + Return Kit GR SUPRA (DB42/DB02) for HKS R/S
$1,430.00
HKS
HKS SSQV IV Kit for GR SUPRA (DB42/DB02) B58
$1,320.00
HKS
HKS JZX100/JZX110 SSQV4+ Return Kit
$407.00
HKS
HKS JZX100/JZX110/JZS171W 1JZ-GTE SSQV4 BOV Kit
$327.80
HKS
HKS SSQV4 RETURN KIT EVO 7-9 CT9A/CT9W
$495.00
HKS
HKS 2015+ Subaru WRX SSQV4 Black Return Kit Plus VAG/VMG
$404.80
HKS
HKS 08-14 Subaru Impreza WRX STI/ 2015+ WRX STI SSQV4 Black + Return Kit GRB/VAB
$382.80
HKS
HKS SUPER SQV4 Black Edition GDB EJ205/ EJ255/ EJ257
$349.80
HKS
HKS Super SQV4 Black Edition FK8
$514.80
HKS
HKS SUPER SQV4 BLACK EDITION UNIVERSAL ASSY
$324.50
When you lift off the throttle, trapped boost has to go somewhere. A blow off valve opens and vents it to the atmosphere, protecting your turbo from compressor surge and producing the familiar "whoosh." Shop vent-to-atmosphere and hybrid blow off valves in universal weld-on and direct-fit designs, by valve size, mount type, and spring adjustability. On MAF-equipped engines, venting metered air can cause a brief rich condition, so many owners choose a hybrid valve or a recirculating bypass valve instead. Shop direct-fit valves by year, make, model, and engine. For flanges, springs, and adapters, see blow off valve accessories.
| P0172 / P0175 | System too rich, bank 1 / bank 2 | Venting metered air on a MAF-equipped engine |
| P0171 / P0174 | System too lean, bank 1 / bank 2 | Valve leaking at idle and drawing in unmetered air |
| P0299 | Underboost condition | Valve leaking or opening under boost |
Under boost, the charge pipes and intercooler are full of pressurized air. When the throttle closes, that air reverses toward the compressor wheel, causing compressor surge, a fluttering sound that stresses the turbo. A blow off valve senses the change to manifold vacuum and opens, releasing the trapped air so the turbo can keep spinning freely and boost returns faster on the next throttle input.
A blow off valve vents air to the atmosphere. A bypass valve recirculates it back into the intake before the turbo. Both protect the turbo from surge. On MAF-equipped engines, the MAF has already measured that air, so venting it commonly causes a brief rich condition. Bypass and hybrid valves avoid or reduce this. See our turbo bypass valves for recirculating designs.
Hybrid or dual-port valves can vent part of the air and recirculate the rest, often with an adjustable split. They're a common choice for owners who want some BOV sound on MAF-equipped engines while limiting drivability issues.
Leaking at idle is common when the spring is too soft for your engine's idle vacuum. On MAF engines, this lets unmetered air in, which can cause idle hunting and lean codes.
Stalling or stumbling on shifts commonly comes from venting metered air on a MAF-equipped engine.
Flutter usually means the valve is too small, too stiff, or not opening fast enough.
Opening under boost points to a spring that's too soft for the boost level.
Blow off valve questions usually start with stalling, idle problems, flutter, or a check engine light after installation, along with questions about sound and MAF compatibility. The answers below cover the most common BOV problems, including leaking at idle, rich codes, stalling on shifts, flutter, and valves opening under boost, plus how blow off valves compare with bypass and hybrid valves. Because valves differ by mount type and some are matched to specific vehicles, confirm fitment on each product page before you buy. For flanges, springs, and adapters, see blow off valve accessories. For help choosing a valve, talk with your tuner or contact our team.
On MAF-equipped engines, venting air the MAF already measured commonly causes a brief rich condition that can stall the engine. A hybrid or recirculating valve, or tuning, commonly fixes it.
The spring may be too soft for your engine's idle vacuum. Increase preload or use a stiffer spring.
The valve may be too small, the spring too stiff, or the reference line too long or leaking. Check sizing and plumbing.
Yes. Venting on MAF engines can set rich codes like P0172, and a valve leaking at idle can set lean codes like P0171.
A blow off valve vents to the atmosphere. A bypass valve recirculates air back into the intake.
No. It protects the turbo and can help boost recover between shifts, but it doesn't add power on its own.
Speed density engines typically don't. MAF-equipped engines may need tuning to run a vent-to-atmosphere valve smoothly.
