If You Are Having Car Problems And Your Check Engine Light Is On, Please Read This!!!
Mechanical Problems/Vehicle Issues and Fix-it ForumIf you've got a problem you just can't figure out, a noise you can't diagnose, or a Check Engine Light that won't go away, ask about it here!
If You Are Having Car Problems And Your Check Engine Light Is On, Please Read This!!!
No this is not another thread on how to turn the check engine light off, but I have another issue to address.
Ok I had to make this thread to shed some light to people.
I have seen several threads during the cource of my time on 7thgen where people are having major issues with there car whether it be idle problems, tranny problems, or whatever and they dont know what to do or whats causing it. then come to find out that there check engine light is on.
Well, lets go over something here.
A car runs off of inputs which are sensors. Now those sensors send information to the ECU (basically send signals to the ECU) and based on those signals recieved at the ECU will determine what the ECU will send to various outputs which are actuators, solenoids, etc... and that is what runs your car
Now if your car runs good, then the ECU sees the right signals and sends info to other outputs and the car runs fine.
Now lets just say (I was use an example that I gave another member a few days ago) that you wake up one morning and get in your car and start driving around and after 5 minutes, black smoke is pouring out of your exhaust, you are getting really crappy gas mileage on your 1000 mile trip and have to fill up every 100 miles or so, and the car barely runs, it boggs down and even stalls out every once and awhile. And has problems starting. And your check engine light is on.
the first thing that people will do is wonder what the hell is wrong with there car. And the first thing they do is overlook the check engine light and start doing everything possible to fix it. Replace air filter, fuel filter, spark plugs, ignition coils, run higher octane gas, whatever so they dont have to take it in to the dealer and have to pay too much money.
Well back to the scenerio, after relacing all of these items, the car still runs like it did before and they give up and take it to the dealer. A few days later you get the car back with a brand new o2 sensor, no check engine light and the car runs like new again and you have a $40 bill for a new o2 sensor. and you are wondering what the hell? You just got done spending over $200 to try and fix it when a $40 part was the cause
Well now you ask how did my o2 sensor cause all of those problems. Well lets take a look. A o2 sensors job is to measure the amount of oxygen in the air before it goes to the cat converter. And based on that reading, the o2 sensor will send a signal to the ECU and based on that signal, the ECU will add or reduce fuel to the engine. Now if that sensor happened to fail and read extreme lean all of the time, the o2 sensor will think there is too much oxygen coming out and will instruct the ECU to dump the engine with fuel to compensate the over lean condition even though your engine is running fine. Now you are running extremely rich and have too much fuel entering the combustion chamber to mix with the air coming in resulting in the black smoke out the exhaust, bad fuel mileage, and stalling. All of these because one sensor sent a false signal to the ECU.
The point I am trying to make with this is if your car is running like crap, your tranny stopped shifting, your car has crappy fuel mileage, whatever and your check engine light is on, dont start throwing parts at the car to try and fix it, find out why the check engine light is on. I have seen people go to the extreme when there tranny fails and the check engine light is on and they replace the tranny cause they think its shot when all that was wrong was a bad sensor. which was a $20 part.
This goes for any other issues to. If your car doesnt start, a bad crankshaft positiom sensor not sending a signal to the PCM to let it know which cylinder to fire. That will cause a no start condition and throw your check engine light on.
Again I made this thread to let everyone know if your car is causing you problems and the check engine light is on to diagnosis that first because usually that is the cause of the major problem you are having. I am just annoyed on how many threads I see daily where people overlook there check engine light.
I am not here to try and explain to you how a car works or try and sound like the smartest person around, I am simply here to help everyone. I love working on cars and I hate when I see people not use common sense when trying to find out what is wrong with there car.
Last edited by streetglower : 10-30-2005 at 09:05 PM.
My dad just told me the other day that his car seems to mis every now and then. He said he will be on cruise control or whenever and it just feels like the car misses once or twice and then it's fine. Rather wierd, I'm going to look into a little more.
I can't imagine not finding out first why the check engine light is on!
Mine came on and I assumed it was the o2 sensor... my father in law has a computer to hook up and read the codes from the car. I brought it to him and it actually was the EGR valve! Glad I didn't go buy a $60 O2 sensor. Instead I needed a $150 EGR valve and gasket!
I have the same exact problem and the code that is coming up is EGR, so I replaced the EGR and Gasket with a brand new one from Honda. Still has same problem. CEL is still there and it is the same code for the EGR - insufficient flow or something like that. Did replacing your EGR solve the problem? It didn't for me. Is there any other sensor or condition that could possibly give the same code? Can anyone help?
Thanks,
Don
Code: P0401 Exhaust Gas Recirculation Flow Insufficient Detected
First post here because I need some help - I just installed a Holley Warlock on my 99 SI and I bought a high flow cat (technically it is not really high flow even though it says that) and my check engine light has been on ever since. I have been driving with the check engine light on for over 4 months. I would like to know if I have damaged the car bad because I am worried. It still runs great and I have done oil changes ever 2,000 miles. Most importantly though I need to know how to get this thing off. It is driving me insane. I have replaced the O2 sensor and cat with brand new ones (yes I bought another cat because they are 25 dollars each) Anyway, one thing i just noticed today is the proper placement of the o2 sensor on my old cat was in the middle, and on the new ones its before the cat. I was thinking this is most likely the issue to why my check engine light it still on considering all the parts are brand new. any advice would be great. I need to know if I am on the right track. Because if I am the only after market Si cats are over 200 dollars (performance ones) and I don't want a stock one because it makes my exaust sound like shit. If there is a cheap way to fix this let me know. I was thinking of saying F*** it and drilling a hole through the middle of the cat to move the sensor so it will work with 96 model civics and up.
the reason why the light is on is because you said you dont have a actually converter in there correct? if there is no catalyst material in there, the light will come on because the secondary o2 sensor is signaling the ecu that there is no cat. also the placement of the sensor in the converter also has an effect. but if the cat converter you purhcased is just a "resonator pipe" then it will stay on. you can get an o2 simulator, but it just turns the light off. search up on it, there are plenty of threads.
Thanks for the tip -Although I read into those more and my car would not pass Echeck. I just ordered the stock cat and it shut the light right off. The only aftermarket one I have seen for my car was made by randomtechnology and costed way too much.
I having problem the car stalled in the middle of driving, after that could not start over. after a few minutes or so, it will start up again, this is happening. the code P1361 was shown when check by mechanic..some even shows TDC sensor "noise", what is taht mean??
