MPScan

The light just came on for the first time this afternoon. My engine appears to run perfect. No trouble idiling, shifting, acceleration, cruising.. and just got 415 miles on a tank of gas last weekend! So things are running perfect.

I read the detailed description, but I am not really great with cars. I reset the Service Engine Soon light, but will it come back on? Are these codes really harmful?

0504 - Automatic Transmission Control Unit Signal to ECU
0605 - Cylinder 4 Misfire
0707 - Rear Heated O2 sensor
0304 - Knock Sensor

So, what should I do?

WielkiWaac

iTrader: (8)

that will cost you couple hundrets

maxima_kenny96

iTrader: (10)

pray that u can fix it for a cheap amount of money.

Ceasars Chariot

iTrader: (16)

ecu codes defined
http://forums.maxima.org/showthread....7&page=1&pp=10

Maximus_95

iTrader: (8)

yeah, its bad, it will cause your car to run like $hit.

I30tMikeD

iTrader: (8)

Those were 3 of the worst responses to a question I have ever read.

Hmmm...you say your car is running well so that makes it a bit harder on where to start. You do have a misfire code, but if it was a bad misfire or a conatant one you would be able to feel it.

What I would do first is reset the ECU to clear the codes and see which ones come back. I would not run out and replace anything at the moment if the car seems to run fine. Only ones that would have me worried would be the misfire and the transmission control unit. The knock sensor and rear o2 sensor are not a big deal. You could drive with a bad knock sensor and rear o2 sensor for ever and it would not be a big deal and the car will run fine...a bit lower on power, but it will run fine. I say just clear the codes and we will and see what come back and we can go from there. If you get the misfire code again your gonna want to pick up a multimeter if you don't have one to do some resistance testing on the coils and injectors.

97MaximaSE

i had the 0504 before when my engine got wet but i reset it and it soon went away..replace the knock sensor and o2 sensor and get a tuneup...you should be good to go.

MPScan

Yea, no kidding. I guess that is how some people treat newcomers. I thought that I was actually doing good, didn't post a "help my check engine light is on??" message. I read the FAQ's and figured out to get and decode the codes. I was just wondering if anyone had a similar set of codes thrown at them.

Now, I reset the light this morning, filled up with a tank of 93 gas (as usual) and took off to some outlet stores. 130 miles round trip. Around 80 miles into the trip, the light lit again. I just got home and did the codes... it threw two:

0707 - Rear Heated O2 sensor
0304 - Knock Sensor

So, like you said, I guess I can live with out doing much right now. So long as my engine runs smooth and my mileage is good, I don't have much to worry about, right?

I also read somewhere that there are 3 O2 sensors on the Max, two in front and one in rear, and actually the only ones that "do work" are the two front ones.. the rear is like a check to make sure the other two are working... is this correct?

Thanks for the help!

S103100F

iTrader: (1)

first reset your ecu waite till you get cel check if you get same codes if you do get same ones start with knock sensor

I30tMikeD

iTrader: (8)

Yes, you can drive like that without any problems. A bad knock sensor will retard your timing and your car will be slower but your not doing any damage or anything.

Your also correct about the front two o2 sensors being the important ones and the rear just monitoring the cat.

I would get use a multimeter to check your knock sensor to see if it actually bad or not. Sometimes you can get a knock sensor code along with an o2 sensor code for some odd reason even if the knock sensor is fine. Or you could just replace them. You should be able to find both sensors for about $150-$160. The rear o2 is real easy to change, the knock sensor is a bit more difficult but nothing to bad if you got the right tools