• Hondata Reflash - Civic Si 2006-2011

Reflash your 2006-2011 Civic Si engine computer - this reflash is for the US and Mexican 2006-2011 Civic Si with K20Z3 engine.

  • Fuel, ignition and cam timing optimized.
  • VTEC lowered from 5800 rpm to 4500 rpm.
  • VTEC window added.
  • Cam angle optimized.
  • Rev limiter increased to 8600 rpm
  • California emissions legal (CARB EO D-742)

This is for an ECU reflash - the ECU is not included.  Hondata does not sell direct - the reflash must be purchased from a Hondata dealer. The ECU reflash form must be sent with your ECU.

Important Notes

This reflash will work well with a variety of aftermarket performance parts. It will work well with:

  • An intake
  • Cat-backs (as long as they are less restrictive than stock)
  • A race header *
  • A combination of intake and race header

(*Note that current race headers eliminate the catalytic converter and will generate a check engine light. This engine check light is for emissions and will not affect the car's performance. Race headers are for off road use only)

You must have a minimum of an intake or header.

It is not designed to work with a stock 2006-2011 Civic Si and will lose power between 4500rpm and 5600 rpm if installed.


The 06 Civic employs a mass air flow sensor that automatically adjusts the air-fuel ratio for increases in air flow from correctly designed intakes and race headers. Intakes for this car are critical. The intake, in particular the size and shape of the piping around the mass air flow sensor, is the primary determinant of fueling for this car. If you have any problems in running rich or lean, then you must retest with the stock intake. Race headers will not cause this engine to run lean.

Sales Region US
EPA/CARB status (USA) CARB EO D-742
Model Civic
Year 2006-2011
Market US
Trim Si
Engine K20Z3
Transmission MT
Part Number 37820-RRB-A04 to 37820-RRB-A14

For consistency in dyno testing we suggest you follow the dyno procedure outlined here.

Power is gained in the mid range from 4700rpm to 6300 rpm. Power gains above 6500 rpm are negligible, although the higher rev limit will raise average power a little.

As this reflash will work with a combination of aftermarket parts we have two examples of the effect of the same reflash on two 06 Civics. (Both Civics dynoed at about 195 stock HP)

2006 Civic Si with Race header, intake and Hondata Heatshield gasket.

The following dyno chart is for an 06 Civic Si with a DC Sports header, Injen intake and Hondata Heatshield gasket. The only change from the green to the blue dyno run was a change from the stock ECU program to the Hondata reflash.

  • 4500 rpm VTEC point
  • Rev limiter raised to 8600 rpm.
  • 15-25 Hp gain midrange
  • 15-29 ft lb torque gain midrange

2006 Civic Si with intake and Hondata Heatshield gasket.

The following dyno chart is for an 06 Civic Si with AEM CAI intake and Hondata Heatshield gasket. The only change from the green to the yellow dyno run was a change from the stock ECU program to the Hondata reflash.

  • 4500 rpm VTEC point
  • Rev limiter raised to 8600 rpm.
  • 10-15 Hp gain midrange
  • 5-12 ft lb torque gain midrange

The ECU is located under a plastic cover to the right of the battery under the hood. You will need a 10mm socket. This is what it looks like - in place and removed from the car.  There are 3 bolts holding the ecu in.  You may find it easier to completely remove the battery, but you will need to enter the codes for your radio if you do this.

VTEC Window

We have implemented a VTEC window from 4500rpm to 5800 rpm.

  • Below 4500 rpm the K20Z3 is always on the low cam
  • Above 5800 rpm the K20Z3 is always on the high cam
  • Between 4500 rpm and 5800 rpm the K20Z3 is on the low cam at part throttle switching to the high cam at full throttle.

The VTEC switch point on this reflash is very smooth - much smoother than previous reflashes. With a stock air box and race header the switch point is virtually undetectable. For the reduction in VTEC "kick" and aural stimulation, we apologize, but this is the path to maximum power.


Nitrous has not been tested. As ignition timing has not been changed, nitrous is as safe to run with this reflash as with a stock ECU.


Aftermarket cams have not been tested.

Race headers

Race header / test pipes will eventually give you an engine check light telling you that you have a faulty catalytic converter. Race headers are for off road use only.

A WHOLE DIFFERENT CAR (from what you'll be used to)... MY LAAAAAAWWWD...what have these people done to my mild mannered car.... sickyute.
Extensive report in this 8thCivic.com thread.

Its everything i hope for and more! The drivavbilty of the car is awesome now, no more hesitation and a lot more mid range pull and top end power. The midrange is where it gained the most power and that's nice because everytime you shift to the next gear you land right in the peak torque section. From stock i have gained 34whp and 31wtq with only a custom 3'' exhaust and DC race header, hondata IMG and reflash. This was all done with factory intake!! - 06redsi.
More info from this 8thCivic.com thread.

Some 2002 onwards and all 2006 onwards ECUs are flash programmable. The ECU can be repeatedly reprogrammed without removing or replacing and internal components.

How do you get your ECU reflashed?

  • Fill out this form
  • Contact your dealer. All sales are made through Hondata dealers.
  • Your dealer or you will need to remove and send your ECU, immobilizer and key to Hondata.

Do I need to send the key & immobilizer?

Only for 2002-2006 RSX and 2002-2005 Civic Si reflashes. All other reflashes do not need to send a key or immobilizer. Flashing the ECU does not in any way alter the immobilizer operation.

How long does it take?

The ECU will be reprogrammed and shipped out the same day it is received. Shipping in the continental USA is FEDEX next day.

Will this affect the fuel economy?

Assuming you drive the vehicle in the same way, no. Fueling at cruise is the same as stock.

Will this affect the engine life?

Provided your engine is maintained correctly this modification should not affect the engine's life.

Will this affect the warranty?

It should not.

Federal law sets forth requirements for warranties and contains a number of provisions to prevent vehicle manufacturers, dealers and others from unjustly denying warranty coverage. With regard to aftermarket parts, the gist of the law is that warranty coverage cannot be denied simply because such parts are present on the vehicle, or have been used. (see Federal Warranty Laws for details). The warranty coverage can be denied only if the aftermarket part caused the malfunction or damage for which warranty coverage is sought.

If a dealership denies warranty coverage (more details here) , they should be willing to do so in writing. Have the dealer describe the failure which is causing your problem AND how the dealer believes the aftermarket product installed is responsible for the problem. Keep an accurate log of all contacts and correspondence in addressing the warranty denial. Hondata will provide any technical information the dealership requires.

With any increase in rev limit there is an increased risk of valve damage. To minimize your risk use the Hondata program with the stock rev limit. All reports of valve damage we have heard have been as a result of miss-shift. The Type S valve springs are good. We have tested a Type S with an 8900 rev limit in a press test vehicle for several months with no problems.

Will any settings be lost?

Your ECU will lose some idle settings and fuel trim when it is unplugged. It will relearn idle automatically if you leave it idling for 10 minutes. As you drive the car it will relearn fuel trim values in a matter of minutes.

Can a Honda/Acura dealer erase this program?

Only if another Honda/Acura update is released could a dealer erase your existing program. If Honda/Acura comes out with an upgrade you are not obliged to have it installed. If you do not wish to have the dealer program installed there is a wire you can disconnect or cut, to prevent reprogramming. The charge for restoring an erased program is $75 (cashiers check or money order) shipping included.  You can also remove pin 7 from the OBD2 port to keep the dealer from reflashing your ecu (DO NOT CUT THIS WIRE).

What about bolt ons?

Most programs have been tested to work well with a variety of intakes and exhausts. No retuning is necessary after an intake is added.  Some programs as tuned specifically for an intake or exhaust, and if so, will mention this in the reflash notes.

If you currently run nitrous, these programs will probably not be suitable due to the ignition advance used. If you want to use nitrous and this program now, you must install a nitrous system that retards ignition.

What about turbo-charging and super-charging?

Use the K-Pro or FlashPro.

What octane is recommended?

For high compression engines (K20A2, K20Z1, K20Z3, K24Z7) 91 octane fuel or better is recommended.  For all other engines there are gains from using higher octant fuel, as the ECU will automatically advance the ignition timing if no knock is detected.

Hondata Reflash - Civic Si 2006-2011

  • Brand: Hondata, Inc.
  • Product Code: Reflash - Civic Si 2006-2011
  • Availability: In Stock
  • $295.00