SKU: 16484300700

Hondata Reflash - Civic Si 2002-2004

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Description

Hondata Reflash - Civic Si 2002-2004Reflash your 2002 2004 Civic Si engine computer. Fuel, ignition timing and cam timing optimized. Rev limiter raised to 7700rpm. 10 12 peak hp gain depending on the dyno and modifications 4 9ft lb torque across the rev range Power peak raised 400 rpm from 6300 rpm to 6700 rpm (higher with headers) 0 60 mph times improved by 1 second. Fully dealer compatible works with all Honda scan tools and equipment. This is for an ECU reflash the ECU is not

Reflash your 2002-2004 Civic Si engine computer.

  • Fuel, ignition timing and cam timing optimized.
  • Rev limiter raised to 7700rpm.
  • 10-12 peak hp gain depending on the dyno and modifications
  • 4-9ft lb torque across the rev range
  • Power peak raised 400 rpm from 6300 rpm to 6700 rpm (higher with headers)
  • 0-60 mph times improved by 1 second.
  • Fully dealer compatible -works with all Honda scan tools and equipment.

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.

We do not recommend the use of nitrous or forced induction for this reflash. For these applications use the K-Pro.

We recommend that 91 octane fuel be used with this reflash.

Warning

Within the USA this product is legal only for racing vehicles which may never be used upon a public highway.

Restriction
Sales Region US
EPA/CARB status (USA) Competition vehicles only
Vehicle
Model Civic
Year 2002-2005
Market US
Trim Si
Engine K20A3
Transmission MT
ECU
Part Number 37820-PNF-A01 to 37820-PNF-A12

 

2002 Civic Si, stock and with K20A3-Si Flash program.

Tuning notes

This tune is for 91 octane pump gas. The reflash has not been tested with 87 octane fuel. In the graph above, the change in octane was worth about 2hp and the tuning 8-10.

We recommend that 91 octane fuel be used with this reflash.

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

The K series ECU, in order to be re-programmed must have a functioning immobilizer system. Three items must be sent to Hondata: the ECU, the ignition key and the immobilizer. The immobilizer works as normal after the ECU has been re-flashed.

Tools needed:

  • Philips screwdriver
  • 10 mm socket and drive
  • Time needed : 10-15 minutes

Removing the immobilizer (Civic Si, RSX / Integra)

Under the steering column remove the three philips screw holding on the bottom plastic cover.

Depress the bottom cover along its top edge where it meets the top cover to separate the plastic clips. Rotating the steering wheel 45 degrees can help.

Lower the steering column and remove the bottom plastic cover from over the height adjustment lever.

Unclip the green connector immobilizer connector and unscrew the securing two philips screws.


RSX ECU removal

The ECU is located in the passenger's footwell. The kick panel is removed after depressing the centers of three small plastic buttons around the front covering panel.

Unplug the three wiring connectors and remove the two front most 10mm locating bolts, plus the rear bolt. The ECU will slide out easily - if it does not, then check that the rear bolt has been loosened or removed.

K20A3 Civic Si ECU removal

The Civic Si's ECU is located in the passenger's footwell behind the glove compartment.

Unclip the lower plastic panel:

Unplug the three ECU connectors.

Remove the lower two 10 mm bolts.

Open the glove compartment and push out from behind the two bump stops. The glove compartment will drop after this is done.

Undo the last 10 mm bolt and slide the ECU down.

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 16484300700

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john w gardner jr
Alexandria, US
★★★★★ 5
Buy!
Color: Black/Negative
Great watch
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Reviewed in the United States on February 22, 2026
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Luna
Alexandria, US
★★★★★ 4
No instructions
Color: Black/Negative
Watch is good, but it came with no instructions bc this is very confusing to figure out. Backlight is great effect and really nice for the value. Easy to see and read
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Reviewed in the United States on May 29, 2026
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Nethercott
Louisville, US
★★★★★ 5
Functional and great look!
Color: Black, Color: Black
This is my third watch I’ve had in the last 10 years. I bought my first one in 2014 when I was doing triathlons. My second one just died after surfing/working in a hospital with it for the last 3-4 years. I could of just changed the battery but for $40 and it will last, I thought hmmm let’s just get a new one. No complaints! Shipping arrived in 2 days, and the price can’t be beat. If you are looking for a simple watch to wear and not having to worry about getting it messed up this is it! I had a garmin 410xt that I had to charge etc but this watch is extremely convenient and comfortable. High recommend!
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Reviewed in the United States on August 30, 2023
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Gregory C.
Boise, US
★★★★★ 3
Not great...
Color: Black/Negative
The dial is so dark that I can barely see the numbers. Very, very disappointing.
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Reviewed in the United States on May 4, 2026
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GARY
Fort Morgan, US
★★★★★ 5
PERFECT
Color: Black
Watch is light weight. Has a good feel on the wrist and easy to read during the day and easy to read with the indigo back light at night. I have large wrists and this size is good. For smaller people it might be to large. The functions work well and its water tight. Its durable and keeps on ticking.
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Reviewed in the United States on September 4, 2024

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