Check Engine Light!

[97NSX]

Hi guys. My nsx keeps on throwing the check engine light on. This is after i installed new headers exhaust and both 02 sensors brand new. Had the local dealer check the car three times (each time it came on) They keep on pulling the front 02 sensor code. We also tried swapping the two sensor. All these items are brand new from science of speed. Now the dealer tells me to replace the sensor with OEM (do both of them) Could the headers be the problem? or defactive? The dealer told me its the 02 sensor that needs to be replaced. Car also runs really rough. All this happened after i replaced those items. Did any one else have these kinds of issues after replacing and installing these items? This is getting really expensive already spent so much on labor and the last time had to tow it 100 dollars, so i am frustrated. The dealer is very reputible and all the nsx guys go to him in the local and surrounding citys. I did my 60 service, timing belt and new clutch there am very happy. He keeps on saying the code is the 02 front sensor, but my car runs weird too. It takes a few seconds before it'll pull. I thought that it wouldnt have anything to do witht he front 02 sensor. the sensors job is to tell the car that somethings wrong some where and that something else has to be replaced. I know that the problems somewhere around these thre items. I spoke to a couple of other guys that know the nsx and they tell me its something else. So this last time when i took my car back to the dealer i told himt o check for otehr things too and he couldnt find anyhting else. I am lost and losing money too trying to find this problem.

 

[Daedalus]

The dealership sounds entirely dependent on code readers. Did they check wiring between the ECU and the sensor connector, and voltage ouput to the sensor? Maybe the wiring was damaged when the header was installed. Bad O2s and CELs will definitely cause performance issues.

 

[smacke-swe]

I have similar problems since I changed to after market headers last week. ( but I haven't had time to look at it yet.. )
But my light up the "Engine" light and the TractionControl light..
I on the other hand was able to reuse mu o2 sensors so I know they worked before the header swap..

I have read somewhere that its very important that you don't get grease, WD40 or similar on the sensors, so that can be a possible problem.

 

[97NSX]

Daedlus thanks for the reply. I well call him early morning and let him know about this issue. One thing that concerns me is that when i was getting the code via the pin method i had 5 slow flashs and 3 fast ones and again 5 slow and 2 fast ones this means code 53 and 52 knuck sensor. The dealer took the car in and after diagnosing it told me its the front 02 sensor. He also pulled the code in front of me again and this time it was code 43 wich he told me its the 02 sensor again. So i dono how all these codes could mean one thing only. I just dont wana buy two new oem sensor for 300 pluss dollars plus instelation and have the same problem a day or month down the road.
If any one else want to add to this i would greatly preciate it and for bring it to his atention asap. Thanks a bunch again.

 

[clr1024]

Try resetting the ECU first, either disconnect the battery or pull the clock fuse for a few minutes. I think this is a fairly common problem after people install headers.

 

[NSXclear]

Here is a cheaper solution that might or might not fix it. But for $3.99 x 2 = $7.98, it's worth a try.

Install the o2 sensor to anti-fouler plugs. This will put the o2 sensors further away. Reset the ecu, by pulling the fuse for the clock for a couple of seconds. I'm using this solution for my straight pipes. Not sure if they will help in your situation.

You can buy them from any auto parts store. You will need the 18mm ones. Just drill them out to fit the o2 sensor in them. I forgot what size drill I used. Use two anti-fouler plugs for each o2 sensor. I try to find the part number for the anit-fouler plugs.

 

[smacke-swe]

ahhh... thats right... I remember that I was told that the O2 sensor on my super seven car had to have a extension since its father away from the engine than original...

Can that be the problem ??

 

[Aero]

Back when I first put on my GTLW exhaust, I got the check engine light the first time or two after it warmed up when I drove it. When I turned the car off, it was gone for a little while. After a day or two of driving it never came on again.

A few months when I think put on headers (with new O2 sensors) I got the exact same thing but after I drove it a few times (the same day) it went off and has stayed off ever since. I was gonna have it checked out if it didn't go off but luckilly it did and never came on again and it ran perfect the whole time the light was on.


How long has yours been doing this?

 

[Larry Bastanza]

I really think you need to investigate the extension cables for the 02 sensors. Check that a pin is not pushed back in the plastic gray connector body making intermittent contact. Also you should check the original connectors for the same thing, it happens.

I have seen this many times and now before I even install headers I check every wire on every connector. If you have just replaced your 02 sensors, I would not do it again, at least not yet.

HTH,
LarryB

 

[NSXFRIEND]

Sorry to hear about your problems. There is one person i know of larry or david Tofik in hilltop tacoma called "Expert muffler". Hey might have some insight on your exhaust/sensor issues.

Good luck

 

[97NSX]

Hi all and thanks for the reply and thank you Larry as well i am on my way to the dealer to show him these replys from you guys and hopefully it'll help him out. I had an old header on and didnt have any problems with it at all. The new one was installed a few months back and was runing fine untill one day when my check engine light came on wich was the fron 02 sensor. I replaced both 02 sensor band new and after a couple of days the light came back on. Went abck to the dealer he checked it and was ok for a couple of days and then came back on. Went back to the dealer he got the code adn told me that its a fualty front 02 sensor again, reset it and did some more work down there. The third time it drove really bad wont take off like it used to so i had it towed yesterday to the dealer and this time he said to replace both 02 sensor with OEM. So i'll go there now and shwo him all these replys adn see waht he'll say. I'll keep you posted later on today. If you think of anyhting else please let me know thanks so much again.

 

[AdvansCPAP]

I kinda had the same problem when I had my headers changed. After the install, the check engine light would turn on intermittently and throw a front O2 sensor code. I was ready to change out the sensor, but discovered the O2 sensor wiring rubbed against the header and caused intermittent shorts. If everything was working fine before your install, and especially if you have new O2 sensors, I bet its wiring thats causing the problem. Use a multimeter and check if you're getting continuity between the wires. Wiggle the wires while doing the check to see if it makes any difference.

 

[97NSX]

Hi guys. Heres an update in my nsx now. Went to the dealer to pick my car up. The nsx teck came out and told me that both 02 sensor are no replaced no more check engine light $565 including labor. He told me that the car still runs alittle funny and he didnt have time to look at that issue. He only fixed the check engine light. After paying i took the keys thanked him and started to drive. As i pulled out of the lot the car started to drive really bad cus it was cold i thought. SO i started driving it two light where i had to stop pulled over. At about 2 thousand rpm the car hazateds when i push the accelerator and doesnt wana go. So i turned around and the tech drove with me and he noticed it but this time the car was warmer and drove alittle better. He told me that he needs the car for more time to look at this spacific issue now. He thinks the the injectors might be clugged but not sure untill he looks at it more closer. So now i still have thier loaner car and no nsx. The 02 sensor did not make a difference at all but iam happy that i atleast have an OEM part.
So waht should be done now? the injectors? ECU? Air box? It feels like theres no gas or its not getting an air i dono really wiered. A few months ago one of the relays or one of the computers behind the drivers and passengers seat would makes this weired clicking sound, and i dono if that has anything to do with it. But i noticed that sounds no more this time. It could be a mis and more expansive. Does any one have any ideas as to what the hell could it be. The car is clean all the service has been done at the this same dealer, no leaks. Did everything, now this. The tech did everything you guys suggested too.

 

[Aero]

Find a different mechanic. I'd demand since the new OEM O2 sensors didn't fix it you want your old ones back on there and your money back. (btw you can buy OEM ones online for like $80)

It sounds like a fuel delivery problem. I'd get a new mechanic who tries to figure out what's wrong instead of making you throw money at replacing everything. I've heard the injectors clogged excuse from mechanics before...its usually code for "I dont have a clue".

Did you do the headers and exhaust yourself? I'd look over everything surrounding the install and make sure something was disconnected accidently.

 

[Whatwasthat]

How long did you drive with the bad 02 sensor problem? Do you get any black smoke coming out of your exhuast when you rev the engine? Maybe you're getting too much fuel. Feel the exhuast coming from the tailpipe.

 

[ef you]

does your new header place the o2 sensor any closer or further away from the engine than the stock header did? this could be causing the sensor to heat up too slowly, which can keep the engine in open loop longer, or even stuck in open loop. you will burn more gas in open loop because the ECU thinks it needs to run rich, and even could cause carbon buildup in your o2 sensor and catalyst. it also can lead to fouled out spark plugs.

its not looking like you have bad sensors, since you changed them out and its still driving badly. you might want to check to make sure that all the wires are plugging in fully inside the connectors, and that you are getting continuity and proper voltage. if the o2 sensor heater isnt working, it will stay in open loop longer.

if everything ir right electrically, you may need to look at position of the sensor on the exhaust system. if the sensor doesnt stick out into the exhaust path enough, or if it sticks out too much, you'll have problems. not enough, and it wont get a good "sniff". but if its too much, itll foul out when carbon gets stuck in it. the primary sensor doesnt have the benefit of a catalyst to filter the gas that passes through it.

if your aftermarket headers dont let the sensor mount far enough in the exhaust path, you might have to grind down the bung so the sensor will screw in further. if the bung is too short, the sensor may stick all the way into the exhaust path and get clogged up.

my guess is, if the wiring is all correct and you have voltage, the sensor isnt in the exhaust path and isnt getting good readings. but this is just a general idea, not an NSX specific one (i still have a stock NSX)

 

[97NSX]

Hello again. Aero everything in my car was done by the same master tech at the same dealership. from the 60k service to timingbelt to new clutch to cam seals to header instelation. Bumper to bumper was done by him. I drove with the bad 02 sensor for about a week or so. Does not smoke at all. All the gauges are perfect too no issues with anything else. About two months or so ago i remember hear this weired sound from the back of the car where the ECU and other electrical componenet (behind the drivers/passenger seat) It was and i think still is a clicking sound each time you press the accelerator, so i am not sure if one of the relays are going bad or maybe its my main ECU box thats bad. This is where i am leaning towards. When i give it gas it'll go click click click. Not sure whats going on. My car is the cleanest and dealer maintained car that i have ever seen. All records from the same dealer ship. Now we cant find this problem. I dont think its the injectors though cus i always putt super unleaded from chevron, how could my injectors be bad i dono about that idea. I think its electrical related and i am leaning more towards that clicking sounds.

 

[Briank]

Clicking main relay is a sign of a bad ignition switch. Have them install a new one and see what happens. Clogged injectors are very rare so don't waste any time or money looking at them.

 

[JCOverNSX]

I have the same exact problem. I got new headers and the check engine light will go on and go off every once and a while. The car hesitates on acceleration just as you said, but not all the time. It didnt happen right away but maybe a month after the install. I took it to a shop and they checked the voltage to my o2 sensors and said they should be replaced. I am using the original o2 sensors but am planning to replace them, hopefully this fixes the problem. I have noticed that my gas mileage has been horrible since the new headers also. I got cantrell headers, what brand are yours? maybe there is a connection there.

 

[97NSX]

Jcovernsx i well for sure let you know whats up this this problem. seems like everyone has this problem of runing bad after changing the headers. I dont have the same headers as you though. How did everyone else solve this problem of check engine coming on from time to time and also the rough runing of the car after wards.?

 

[NSXFRIEND]

I am not a mechanic but here are my suggestions. Leave the car with the dealer and dont rush him. Tell him to take his time, let him have ownership of the issues. Sounds like he guessed the problem and did not get very intimate with it. Here is your checklist.

1. Battery replaced/clean it?
2. Engine ground making proper contact (Alot runability issues/false codes)?
3. replace the main relay.
4. fuel filter replaced?
5. Oxygen sensor/temperature control sensor?
6. Fuel lines clogged/airbox free from elements?
7. Ignition system/ main wires.
8. Check all wires/sensors around headers/exhaust.
9. Borrow an ECU from friend see if it solves problem.
10. Replace fuse box (long shot).
11. Put your stock headers back on see if problem is solved

Keep us posted

 

[Larry Bastanza]

seems like everyone has this problem of runing bad after changing the headers.

No, I have installed more sets then I can count and have never had this issue, except for bad cables. Next thing to check(which I have seen many times) is if they have mistakenly switched the front and rear 02 sensor wires. This will cause the symtpoms described in regard to the poor running.

The front 02 sensor gets relocated towards the rear of the car and it is really easy to swap the cables. You need to run the front 02 sensor wire from the back, over the engine, to the front connector located on the front valve cover.

HTH,
LarryB

 

[Aero]

+1 on the crossed wires.

I have Cantrell Headers and have had no running problems. Only an increase in HP as a side effect. :smile:

No, I have installed more sets then I can count and have never had this issue, except for bad cables. Next thing to check(which I have seen many times) is if they have mistakenly switched the front and rear 02 sensor wires. This will cause the symtpoms described in regard to the poor running.

The front 02 sensor gets relocated towards the rear of the car and it is really easy to swap the cables. You need to run the front 02 sensor wire from the back, over the engine, to the front connector located on the front valve cover.

HTH,
LarryB

 

[97NSX]

Hi Guys just wanted to update you on my car. The tech thought it was the bad coil that was causing the problem, we replaced it with a new one and the problem still didnt go away. Next is to clean the injectors dono a week later still no success! He tried everything that was sugested on here and still nothing!!! Gos knows how much more money.

 

[Briank]

Did you do anything with the ignition switch?