2001 Hyundai Elantra Himy Takes About 5 Mins Check Engine Light Come On

Again you will have to get your codes read and let me know what the exact code numbers are and i will be more then happy to help you when you get me those codes.Please post all replies on this question if you keep posting new questions i wont get a email to let me know you posted a reply and it will make it very hard for me to help you.

Mechanic read cod PO136(indicates after cat O2 sensor)-replaced and code re-appeared within 10 mins.-he is now backtracking the wires which today I found out were good as well as the connectors/voltage-next he is going to replace the 02 sensor again with a different aftermarket brand to counteract a possible short inside the sensor-finally if that dosen't do the trick the ECu may need replacing-thats the game plan-could it be that a Hyundai needs to have a Hyundai sensor or is aftermarket OK?-big difference in price. Please reply back this has us somewhat baffled me more than him, any advice much appreciated.

I have never heard of you have to use the factory o2 sensor to get the code to clear.I would also have him check for open terminals where the sensor plugs into the harness that would be the best guess.ALso wires shorted together i posted the trouble for that code for you to look at.I really doubt its the ecm thats the very last thing i ever suspect.

Thanks-I will pass it on-he did check all the wires for open circut and shorts-he relayed to me all was good/also voltage good but may not be reducing itself to 400 properly.

Alright keep me posted.

Hi Again

same issue-everything checked out-voltage right but it seems it doesn't whant to kick down from start uo(keeps running rich)-took out rear O2 sensor and very carboned up-also could a severely leaking(running) valve cover throw off the front O2 sensor(via the PVC valve) so the rear sensor misreads mixture as needing to be rich, so it never kicks down voltage required?

I really dont see that happening.I thought your replaced the rear o2 sensor?Its already allcarboned up?Is your car burning a lot of oil?

Thanks again for replying!

No the car is not burning oil at all-exaust is almost completely non-existant except for at start-up and then is can barely be seen. It seems very clean and runs very smooth, only leak is a very sustancial leak not from the head gasket-(compression test done and all is within specs)but leak from valve cover itself(gasket was replaced)-valve cove is on order and will be replaced

So does the code come back as soon as you clear the code?

no-it takes about 15 mins. till the car/sensor heats up

So when the sensor heats up and you clear it then it will reset that code right away?

Yes-my local mechanic clears it by use of the scan tool at the garage at the computer-then the CEL comes back on in a few minutes-I'm stumped-have you ever heard of a CEL being so hard to diagnois-again the code reads PO136- could this possibly be a ghost code-hiding some other code?-I really appreciate your time and suggestion in attempting to walk me through this frustrating problem.

A intermintant code that doesnt set instantly can very difficult to diagnose.I have spent a great deal of time diagnosing those types of codes myself.Very time consuming and very frustrating you just have to keep at it.Hopefully it will get worse and will show itself.

Hi

Thanks for all the help-I think I will just bite the bullet and take it to a dealer to diagnois due to the complexity-they have the state of the art diagnois machines. -with technology come a bigger price tag

They also have the day in day out expernice of those brand cars which can be priceless.Let me know what they find.

I just took the car into a dealer of Hyundias and there were multiple problems-open terminals/bad hidden connector and an intermittent bad sender wire to the computor-its all fixed now and I just wanted to keep you updated

thanks again

Your welcome glad to hear you got it fixed.I mentioned check for open terminals i have seen that before.Thanks for the update to help others out with the same problem.