Check Engine Light - Page 2

it could be a number of things. i would started by getting the O2 sensors CHECKED. do not get them replaced unless you want to pay $150 a piece. get them checked to make sure that they are the problem. if they are not the problem, then get the cats checked. they can also cause similar problems.(however, usually it also gives a code for the cat). if none of those are the problem, then you may want to check the MAS.

have you done any modifications to the car? is it still stock?

the only thing that is throwing me away from the 02 sensor being the problem is that when mine went, it told me exactly which bank was the problem, but definetely at least do what eclisped4u said.

That's a good point eng... I was kinda thinkin the Cat but hen again also the O2 sensor... It's in that area obviously though... Or a break in the wire somewhere...

The only mod on the engine is an AEM CAI. BTW: How do I specifically check the O2 sensor?

If I'm not mistaken you check it by the voltage coming from the wire... If it doesn't change at all then you know it's got a problem.

If a car is running the O2 sensor will vary in voltage. For example the Heated O2 sensor on my 93 2.0L goes between 0 to 1 volt while the car is running depending on the O2 output in the exhaust. Now when you initally turn the car on 5 volts go from the O2 relay to the senor to heat up the element in the sensor. To check a sensor you need to turn the car off and check the OHM reading of the sensor. Unplug the sensor from the connector. Check on the net for the specs as to what your sensor should be reading. I recommed that you take two readings. One while the car is cold and hasn't been run yet and the next one after the engine warms up. check to see if the OHM reading is the same in both conditions. I am not sure how the V6 is setup Exhaust wise but there could be up to three O2 sensors. One for each side of the exhaust and one should be after the CAT somewhere. this allows the ECU to adjust the fuel trims. SAFETY NOTE: DO NOT CHECK OHM READINGS WITH IGNITION SWITCH ON! It will damage the Ohm meter and could casue a shock to you as well. Hope this helps. Good Luck

quote:

ORIGINAL: ictponder

The only mod on the engine is an AEM CAI. BTW: How do I specifically check the O2 sensor?

When did you install the intake? was it recently? Reset the battery and see if the light comes back on first.

And SANG I was thinking the Cat as well because on sensor is proir to the cats and the other is after. but Deff try the sensors first and work from there.... And reset the battery and make sure it comes back on, also for kicks and giggles make sure the gas cap is on tight cause that can trip a code but it is usually differnt I think Pressure or fuel pressure somehting like that. Just suggestions

CAI was installed awhile ago, so I don't think it's that. I'll test the sensors tomorrow at work.

If the gas cap isn't tight you'll get a vac code nothing even near the O2 sensor code. I figure the O2 sensor would be easier to test vice trying to tell if there's a cat problem. If the O2 sensors are reading fine and resistance is in spec then the only thing it CAN be is the caty.

I hope not, $115 for a sensor isn't my idea of fun spending. It only cost me $11 to replace an O2 sensor on my old '94 Dodge. I guess all I can hope for is that only one of them is bad. Would still be cheaper than replacing the Cat though.

Exactly the reason I said to check the O2's first easier to check cheaper to replace....

It may actually be worth it in this case to take the car to a mechanic or the dealership. You can get a code read for free at autozone/advance (oh yeah, all cars after 1996 use ODBII computers) but what they use is a simple reader which is basic at best. Most mechanics and all dealerships will have a scan tool that goes much more indepth than a reader will. I am having a similar problem with my 97 Eclipse RS and the reader at autozone didn't help a bit.

A reader is a reader. It's gonna give the mechanic the same thing it gives Auto Zone. The only difference is the Snap On Scanner II will tell them what the code means instead of having to look it up online or in a book. There's NO difference in what it will tell though. The difference is that the mechanic will tell you right there the same things we'll tell you here AND he'll charge you to tell you it.

So if I use a multi-tester. How would I go about testing the sensor? What would be the best setting on my tester to test with?

well if it is the cat then time to get an upgrade...

Screw that just hollow that pig out and call it a day ... Upgrade enough for me lol. I can't remember for sure but you test the O2 sensor for Voltage I think... Shouldn't be a massive amount of voltage but I'm pretty sure it's DC volts...

First you don't want to hollow out your CAT it will actually degrade your preformance not increase it. If it is the CAT just upgrade with a High Flow one. There was an article in Sport Compact Mag about 3 years ago that addressed that and I know a person who did it and his performance went down, not up.

OK to test with a multi-meter First get a Haynes manual so you know what pins you will need to hook up to. I don't know for your car. You need to find the DATA pin and GROUND pin (Usually pin 1) now that you have the pins found set you meter to DC Voltage. Voltage will not go over 5 so a setting close to that will work. Put the black test lead to the ground pin and the red lead to the DATA pin. Have a helper turn the car on but do not start. you will see a raise and lower on the voltage. You want to count the up spikes. For example. IF the error code for a bad ECU is 000 you would not see the voltage raise at all. If your code was 007 then you would see no voltage a raise and fall then another rise and fall. That is the binary code for 7 (though I might be wrong its been a while since I have converted binary). the interval between binary bits is about 1 sec. if after 3 to 5 secs you see it rise and fall again that is a second code. To see the code again you will have to turn the car off then back on. The Haynes book should have the waveform (used if you have a ociliscope) and output signals for this kind of test. The book can also explain the test in more detail this is just a quick and dirty version

Hello guys needing help on my 94 GS. Check engine light comes on then goes off after about 4 minutes... it stays off for about 5 minutes then comes back on and stays on. I was told the 94 model doesnt have an OBDII instead it uses an OBDI. I do not think any Auto, Zone Advanced or Pep bos have a OBDI scanner. Would anyone be able to tell me where I can rent or buy an OBD scanner or would it be less expensive to just have it done at a shop. I own an OBDII scanner already but it is useless on this car. I am a newbie on this forumbut I am a member of the Nissan Forums, Toyota Forums and BMW Forums since I also own a 95 Nissan 200 SER, 2002 Toyota Tundra and a 1998 BMW Z3 and have been able to get a lot of help from those boards/foums I am faily knowledgeable and have a fairly well equipped workshop in my basement.

Why are you posting this in here?