DC2R Engine Light Plus Low idle when coming to a stop..? please help much appreciated

[AK Type R]

Hey all, have had my dc2r for a few months now all has seem to have gone perfect except 2 months ago i lost my license and last week my dad went for a drive to take the car to work and bent the headers where it meets the cat btw my headers are tri-y headers and where they meet into one they were bent, i got that all fixed and as soon as i left the exhaust shop the engine light came on .. i figured it was just oil or something so gave it a minor service just oil and oil filter and the problem is still there the engine light is still on. Yesterday me and my friend went for a drive and i noticed the car dropping its idle when i come to a stop .. the car doesn't turn off just drops to around 400 then goes straight back up to 1000, just wanna know whats wrong before i take it to a mechanic and charges me hundreds for a possible simple fix... thanks guys your help is much appreciated. Cheers.

Mods are Headers, buddy club spec 2 racing exhaust , injen intake , cusco catch can , aliminium radiator, heavy duty fans.

[dc2r-0636]

did they put the oxygen sensor back on?

[AK Type R]

if thats the sensor that goes onto the headers yes they did .. i had a look at it and its all on ..

[dc2r-0636]

maybe its busted then ? coz if the o2 sensor is gone the engine check light will be on.
and the reason i think its the o2 sensor coz it happened as soon as you left the exhaust shop.

DIY on ozhonda http://www.ozhonda.com/forum/showthread.php?8218-DIY-CHECK-ECU-for-j00-!

[AK Type R]

Thanks guys car should be fine now turned out to be the o2 sensor took it to the mechanic getting fixed now . cheers