EPS warning light on Hyundai i20: How I fixed it myself & saved Rs 1500

After letting the technician screw around with my car for a bit with the OBD2 scanner, I asked if I could try it myself.

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I had given my i20 CRDi for wheel alignment to an FNG and requested them to also reset the steering angle sensor to ensure the EPS doesn't keep trying to "center" the steering wheel to a slightly wrong angle.

Sadly, while driving back home, turning the car off and then back on led to the EPS warning light turning on:

Power steering still works but it has become weird. It works now even in ignition-on mode with the engine off. Also, it has become slightly harder when not moving but extremely light at low speeds and back to being hard during high speeds. All in all, I'm taking the car back when I can but I am interested to see if anyone has faced anything similar. Both Hyundai dealerships near my locality have closed since covid and the nearest dealership is 2 hours away hence why I gave it to a 3rd party garage.

Update 1

I have been researching the problem online and found this troubleshooting guide for Hyundai EPS.

Initial hypothesis: My ASP has not been calibrated the proper way. Will take it to the garage tomorrow and see if they will let me use their tool myself.

Update 2

Went back to the garage. After letting the tech screw around for a bit with the OBD2 scanner, I asked if I could try it myself.

Make sure the engine is off and the ignition is on (2 presses on the start button without pressing the clutch)

Under EPS settings in the ECU, you get a few options.

Now, this is what you need to do:

1. Select special operation.
2. Select EPS type recognition. This shows you the preset tunings available for the electric power steering. In the Indian spec i20, there seem to be only 2: DSL and GSL which probably stand for diesel and gasoline (petrol). I chose DSL. In international models or in higher spec Hyundai cars such as the Sonata and Santa Fe, there could also be hard, soft, GSL, sport etc which will all change the feel of the electric power steering. If someone has the patience and knowledge, they could probably write an entirely new map for the Indian spec too with emphasis on steering feel and feedback.
3. Once you perform the update, turn the car off for 20 seconds and then turn it back on again. Only then hit OK on the ECU scan tool which will verify that the update was done correctly. This was the step that the garage tech screwed up which lead to my car displaying the EPS warning light.
4. Go to ASP calibration. ASP stands for absolute steering position and this value being slightly off is what leads to the car not going straight after a wheel alignment. The ECU reads this value and will try to electronically "straighten" the steering wheel towards the dead center whenever you finish turning. Now with all the new cars coming with ADAS, I assume a lot of people are going to be having this problem if they get their wheel alignments done outside.
5. The software will ask you to place the steering wheel as straight as possible and then click okay. I kept it just a tiny tiny degree more to the right to counteract the left pull.
6. Repeat step 3.

And that's it. The EPS warning light was now off and I tried turning the engine on and off a few times to make sure everything was alright. Took it on the highway to test whether it was going straight and it was! Let go of the steering wheel and it was still going perfectly straight. Finally, the steering was back to just how it was when I bought the car and I didn't have to go to a Hyundai dealership and pay an outrageous 1500 rs for their poorly calibrated alignment just to have the ASP angle reset.

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