Parts Now Pay Later with
Log In Cart
Log In

Create An Account

Log In Cart
Your Cart Is Empty
Free Shipping Over $199.99

Free Shipping Over $199.99

Orders of $199.99 or more ship free within the continental U.S.

Shipping Policy

Hondata 02-04 RSX Base Manual ECU Reflash

Images may be for reference only

Hondata 02-04 RSX Base Manual ECU Reflash

★★★★★ ★★★★★ 6 Reviews
$290.00 & Free Shipping

Reward Points

It pays to shop with K Series Parts and our reward points program! For every $1.00 you spend you earn reward points.

They are easy to earn, just log in to your account when you check out. If you don't have one it is free and easy to setup.

They are easy to use during check out. Click on the "Have Reward Points?" on the shipping and payment selection page.

Reward Point Program Details

You earn 2 points for every $1.00 that you spend.

100 points equal a $1.00 discount.

Maximum discount per order is 5% of the order total.

There is no minimum order total to redeem points.

Points do not apply to shipping or sales tax.

Points are not redeemable for cash.

The point value per dollar, points earned per purchase, and order minimum are subject to change.

Earn 580 reward points. Learn More

Because of the ongoing situation with COVID-19 Hondata is taking at least 2-3 weeks to process ECU's.

Monday-Friday: 9am-4pm MST


The 2002-2004 RSX Base Manual K20A3 Hondata refash program advances the ignition, alters the cam timing and optimizes the fuel for a cold air intake headers and exhaust, adding 5-10 ft lb across the rev range.


  • 5-10 HP increase across most of the rev range.
  • 10-12 ft/lb torque increase under 5000 rpm
  • Rev limiter optionally raised to 7300 RPM
  • No measurable difference in emissions from stock.
  • Fully dealer compatible - works with all Honda scan tools and equipment.
  • More torque than a stock K20A2 Type S under 6300 rpm. (see graphs above)
  • This program was tuned specifically for a cold air intake, as they give the best power gains. 
After you order you will receive two emails; one with full instructions on where and how to send your ECU to Hondata and another with the form that you need to sign and include with your ECU.

You are required to send your ECU to Hondata for this service. This product is final sale.

Not legal for sale or use in California on any pollution controlled motor vehicles. See for state by state emissions requirements.

WARNING: This product may contain chemicals known to the State of California to cause cancer or birth defects.


Brand: Hondata
Part Number: K20A3-M
CARB Approved: No

Vehicle Fitment

Acura RSX
2002 Acura RSX Manual 2003 Acura RSX Manual 2004 Acura RSX Manual

6 Reviews ★★★★★ ★★★★★

★★★★★ ★★★★★
5.00/5.00 Stars out of 6 Reviews
Write a Review
5 Most Recent Read All 6 Reviews
Best bang for the buck
Johnny Gutierrez | February 19th, 2018
I like the street drivability of the base model Rsx. This reflash definitely improves that drivability of the base even further. I would recommend the increased rev limit to benefit the that laggy 2nd to 3rd upshift. This is by far the best upgrade you can do for the base RSX.
Holy crap it works!
Christian Polanco | June 18th, 2014
So here is my review, Holy crap it works. So I went through Kseries online. They emailed me the instructions and they were very helpful. I shipped the ECU and the immobilizer on a Monday and it came back Thursday noon. I went through USPS next day shipping. Not bad for going from Maryland to California and back. So when it came back I plugged it in, let it idle for 10 minutes and drove it around. It actually moves now. The main difference for me is shifting from stand still. I really dont feel like Im going to stall now. Just give it slight gas and it just moves, no more shudder. The next thing is chirping. Now my tires are in good condition. When Im gunning it, it chirps 2nd every single time. I was surprised to have it chirp a little from 2nd to 3rd, but then again I was borderline redlining. But as far as rough torque, it hasn't changed. The behavior of the torque actually feels like it has a pair of balls now. I had to wait and wait for it to speed up in. Now the power delivery is just smooth and doesn't lag like before. It use to take me forever to go from 50-100. I would have had to really be pushing it hard and for a long time. With the reflash, that needle just moves. I glanced at my speedo when I was pushing it, and I said, "Holy shit IM doing 100 already???" I was still on 4th gear doing 5-6K rpms. I disconnected the battery for 5 minutes, reconnected and had it idle for 10 minutes and took it out for another drive but to be honest I really didn't notice much difference from the first drive. Like people said before, it changes the driving dynamics. Whatever hondata did, it feels like they spread the power throughout the power band. So the K20A3's power is transferred in a more usable power-band starting at 3K RPM. Unlike before the flash where all the actual power was in 5K and up range. We all know to get to 5K you'll either have to punish your clutch by downshifting to 3rd or just wait until you get there; which by that time the other car is already out of there. So in conclusion, before I couldn't feel myself get pushed back against my seat when I was gunning it. But now I can. Mods at the time: AEM SRI, Apexi N1 Muffler.
Tottaly worth the money
Mrh239 | January 27th, 2012
this is the easiest and probably the cheapest you can get for your base RSX that will make a significant difference in engine power and overall car driveability. Before the upgrade you get virtually no power under 3000 rpms with the AC on. Now the car has improved torque at any rpms. If all you need is a little more power for your RSX and this is the car you drive every day, get the reflash and you will be very happy!
Rex Hamilton | May 17th, 2010
I sent my ecu off on thursday got it back monday, and i can say its worth every penny! my 04 rsx will get up and go now!
Josh G. | February 4th, 2010
I was a little hesitant to purchase the reflash at first since I own a base model. the install was super easy, as I went to a shop just a few miles from hondata physical location. you can feel the difference in power and torque! I also have the greddy EVO II exhaust and AEM V2 intake, along with the reflash and royal purple oil, my base now puts down 200BHP(up from the stock 160) and somewhere around 170-172WHP, with much more torque than a stock K20A2 (I totally broke off a stock typeS on the freeway). the optional raising of the rev-limiter really helps to stay inside the power-band, and tho advertised to raise to 7300, mine will strech all the way to 7600 before it bounces off. I also purchased the gates racing serpentine belt, as my serp belt slipped off the pulley due to the extra RPM of the reflash causing my tensioner to need replacing, although I did have 119,000 at time of install. all in all, definitely worth it, as long as you have intake and exhaust to back it up!
Read All 6 Reviews