Ok I've been getting the same two codes thrown all summer. 1st one is Knock Sensor, 2nd one is Catalytic Inefficiency. As you can see by my sig I've got the usual bolt on's plus I'm running NGK Iridium IX's. Didn't start getting the codes till after the high-flow cat and exhaust was put on.
I'm pretty sure my Knock Sensor is fine, I have no performance issues at all. My car runs like a champ and have been getting an average of 25mpg highway even with AC on. I'm concerned that one or both of my oxygen sensors is bad. Could that be throwing the codes I'm getting? I usually just have Auto Zone pull the codes and reset, do I have to worry about doing that for extended periods of time, or is it OK? The guys at Auto Zone say its because of the crappy gas in our area, and I'll admit I've been running mostly 87 octane, but I have tried 89 with no noticeable difference.
Thanks in advance for all your help.-Bill
Engine Codes and how to fix?
The knock sensor will only through a code if it is an open circuit. It will not set for any other reason. It will also NOT trigger a check engine light. The PO420 cat effecency code your getting will set the light. You are getting the code likely because the high flow cat is not effecent enough for what the ECM expects to see. The ECM watches both O2's to determine if the cat is working right. What it does is compare O2 sweeps. If the 2 O2s sweep within 75% of each other it will trigger the code. So as you can see a bad O2 will NOT cause this code. Since it compares both O2's if one went bad it would be seeing to completely different readings. Indicating the cat is 100% effecient. Further more if the front O2 locked it would throw codes such as PO171 system lean ,Or PO138 O2 sensor malfunction. I honestly feel your high flow cat is your problem.
Re: (NISTECH)
Always kinda figured that was the reason. So other than pulling the bulb or ignoring it, there is nothing that I can do to fix the problem, unless maybe getting the ECM re-flashed would do the trick. Personally I'm all for ignoring it, I'll just save up some money to buy my own code reader, any suggestions on what brand to get for home use? Thank you so much Nistech you truely are the man!-Bill
There is a consult interface tool alot of these guys use. It has similar funtions of the consult. I have not used it but have read some things on it. This would probably be your best option and as I recall it was not all that expensive. Do a search on it here in the forums. It is posted somewhere on here where to aquire the unit.
You could try having the ECM flashed to ignore it or pull the bulb as you mentioned.
You could try having the ECM flashed to ignore it or pull the bulb as you mentioned.