The AEM 21-686C Performance Cold Air Intake System produces horsepower and torque gains by replacing your vehicle's restrictive factory air filter and air intake housing. This air intake system is designed, tuned and dyno-tested to fit specific Honda Civic models. Air enters the system through an oversized AEM Dryflow synthetic washable air filter for outstanding air flow, filtration and performance. The air filter is located above the driver's side wheel well which is designed to reduce intake air temperature and increase horsepower. The intake tubing is constructed from mandrel-bent aluminum featuring a durable gunmetal gray powder coated finish. This air intake system was developed to accommodate the engine's factory emissions control devices including the mass air flow sensor and PCV hose. The cone shaped AEM Dryflow air filter is made from an oil-free, synthetic filter media that can be used for up to 100,000 miles before cleaning is needed (depending on driving conditions). The air intake system is backed by AEM's Lifetime Limited Warranty. Some AEM air intakes are not legal for sale or use in California and other states adopting California emission standards while others are 50 state legal. View the 21-686C vehicle applications to determine the legal status for each vehicle.
- Increased horsepower
- Tuned and dyno-tested to improve acceleration and engine sound
- Low restriction aluminum tubing
- Air filter lasts up to 100,000 miles before cleaning is required (depending on driving conditions)
- Washable and reusable oil-free filter media
- AEM Lifetime Limited Warranty
Installation PDF
Installation Instruction Sheet
Dyno Chart - 2009 Honda Civic EX 1.8L 4HP Gain
| Estimated Horsepower Gain | 4 HP @ 3800 RPM |
| Replacement Filter | 21-201DK |
| Air Filter Color | Red |
| Air Filter Material | Non-woven Synthetic |
| Air Filter Outlet Shape | Round |
| Clamps Included | 9 |
| Clamp Material | Steel |
| Clamp Style | Regular |
| Couplers Included | 1 |
| Product Style | AEM Cold Air Intake System |
| Intake Pipe Color / Finish | Gunmetal Gray |
| Intake Pipe Material | Aluminum |
| CARB EO Number | D-670-21 |
| Street Legal In All US States | Yes |
| TUV Approved (Europe) | No |
| Weight | 10 lb (4.5 kg) |
| Product Box Height | 12.25 in (311 mm) |
| Product Box Length | 20.25 in (514 mm) |
| Product Box Width | 12.25 in (311 mm) |
| Mounting Hardware Included | Yes |
| Warranty | Limited Lifetime |
| 2011 Honda Civic 1.8L L4 Gas Except GX Street Legal in All US States: Yes CARB EO Number: D-670-21 |
| 2010 Honda Civic 1.8L L4 Gas Except GX Street Legal in All US States: Yes CARB EO Number: D-670-21 |
| 2009 Honda Civic 1.8L L4 Gas Except GX Street Legal in All US States: Yes CARB EO Number: D-670-21 |
| 2008 Honda Civic 1.8L L4 Gas Except GX Street Legal in All US States: Yes CARB EO Number: D-670-21 |
| 2007 Honda Civic 1.8L L4 Gas Except GX Street Legal in All US States: Yes CARB EO Number: D-670-21 |
| 2006 11 L4 Gas Except GX Street Legal in All US States: Yes CARB EO Number: D-670-21 |