I own Honda City 2006 1.3 manual. Last Wednesday, i was driving on a very bumpy road, it was dark, a rock hit me from underneath and engine light turns ON.
Next day i went to Suntec(peco road Lahore), they did a computer scan and told me to replace HO2 sensors(both S1 and S2). I was not convinced.
On Friday i visited Honda City Sales(ferozepur road), they charge me Rs 1,000 to do computer scan, and told me to change just one HO2 sensors(S2 the one in the bottom). i took the picture of scanned result from my cell phone and left.

I asked for quotation of HO2 S2 sensor from 3 workshops, Suntec(Rs 4,000), Honda PitShop johar town(Rs 6,000), and Honda City Sales(26,000).

Suntec and Honda PitShop quoted me bilal ganj sensor, while Honda City Sales quoted me new sensor.

On Saturday I went to Bilal Ganj(try to visit bilal ganj on working day Mon-Fri if you want to avoid rush), visited few shops and found a sensor for Rs 3,000, get it fitted by an electrician but it didn't solves the problem, CEL was still ON, electrician said that there might be some problem with my wiring, he said that he will charge Rs 1,500 to check/fix the wiring and will do computer scan, and it might take an hour of two. anyway i had no choice, agreed to him, he took 10mins max, and the CEL turned OFF, but as you guys now our local mechanics/electrician, he didn't stopped and opened another part of dashboard and start checking it with his tester. I told him "mera tery sath 1500 done hy, agar to 5mins me b kry ga to tujy 1500 he don ga". after that he took another 5mins max and said "sir g fix ho gia hy, ao test drive lety han", we took a test drive and he start packing. Problem solved

When i came back home, and saw my sensor(old one), remove the tape wrapped on the wire, if find that white and grey wires were not connected between sensor and connector. the sensor might be in good shape.

Lesson leaner:
1- if CEL turns ON, visit Honda and get it scanned, take a picture of it and search that code on internet.
2- Visit a local electrician ask him to unplug the sensor, and check the wiring.
3- Most probably you will find issue in wiring, as sensors don't get damage easily.

Hope this experience help someone