Hey guys, my check engine light came on tonight. Code is for the cat not under threshold.

Well, i bought my car not even 1.5 months yet. I installed a hks exhaust 3 weeks ago and have driven about 2k miles, no problems.

Monday I reset my ecu, drove for about 10 miles no problems. Filled the tank at a gas station i do not normally fill up at. Drive 5 miles later and CEL comes on.

I do not have a test pipe so i should not be throwing this code, only thing i believe could throw this code is if i have an exhaust leak or could it be the bad gas? Maybe it's the super cold temperature? Anyone else have this problem let me know.

Thanks.

Louis

 

P0420 Catalyst System Efficiency Below Threshold (Bank 1)

 

I dont think having the wrong octane would cause that code.


Edit again: nevermind the second poster changed his post.

 

i didnt think so either, but it's too coincidental it happened 5 mins after gas from that station. When i have been driving that car a lot and this is the first time this has occured.

Louis

 

If you burnt out your cat that fast, you would have been pumping enough fuel down the exhaust to burn it out that fast. I think you would have noticed the engines running condition if that was happening.

 

no the engine ran fine till cel came on, then it ran like crap. Checked the code, reset the ecu and it was all good. Also, the first time i reset the ecu, I did not do the idle learning procedure. "hold gas at 3k rpm for 5 mins....." This should not cause any problems with the cat not lighting off. I believe the cat is not running hot enough and threw a code.

The idle learning procedure does work and speeds up the ecu learning process, my idle has improved quite a lot compared to before. No more dips after a rev.

 

Perhaps the cat is damaged mechanically or there is some type of restriction in the exhaust. The code pretty clearly points to an exhaust system (cat) problem.

 

Do you hear a rattle? Many of us have had the converter physically fail and break loose inside.


fltsfshr

 

Well when it's cold out, recently i hear an exhaust rattle when it's droning, but it goes away. It only rattles when i let the clutch go too slowly and the rpms drop too low.

The s2k clutch is weak, i cant really move the car without adding gas. My other cars, i let the clutch go a little and it moves the car rather easily. When i do it on the s2k, the whole body shakes so much. It's rather annoying. Also happens on some evo's i've drove.

 

It is a high reving motor, that has little to no torque power at low RPMs.