Service Engine Soon light
 

So this morning, I threw the SES light. What would you check first - here's my set-up:

First, I had an oil change about 50 miles ago. And yes, the gas cap is tight. After reading that the SES is emissions and may affect mpg, I checked and my mileage has gone from around 24 pre-oil change to 18 after.

I've got K & N filters and the Z1 Post MAF tubes. Both have been on there for about 6,000 miles. Also have the FI high flow cats (resonated) and FI exhaust (resonated). They'be been on for about 6,000 miles as well and no codes.

I did some searching on here and the only thing I found that could make sense is the temperature. It's about 25 here today, which is the coldest it's been sinve I've had the mods on. Found one post about it being cold out & throwing a code with non-stock intakes.

So what would be your approach to check it out?

First find out what the code(s) are by having them read. If you don't have your own code reader then try Autozone which can read them for you for free.

Once you have the code(s) then you can begin effectively troubleshooting the car.

I was going to say the same thing. GMTA heehee.


scottIN, if you plan on doing any more mods or tweaking the mods you have made, an OBD/CAN tool will probably be a good investment.

Okay, go the codes read:

P0159 (3 times)
P0139 (3 times)

She said it was showing it as the O2 sensor.

P0139

P0159

Not sure what mods you have but I'd checking for intake leaks. It's hard to believe that both O2 sensors failed at the same time. It's also hard to believe that an exhaust leak appeared on both banks at the same time.

I figured those were both banks. And I thought the same thing - weird to have problems in both at the same time since they're essentially independent.

I didn't have them clear the codes, but I just ordered a code reader and will first check for leaks, clean at least the front senors, erase the codes and see what happens. At least now I'll have my own reader - I thought they were like $300 but I found a highly rates one on Amazon for $42.

Mine gets similar codes all the time, and usually it's the O2 sensors faulting. The dealer will replace them under warranty in most cases, unless they are shady and try to blame your HFC. The light will go off and stay off for a while, but has always come on again later on as temperatures vary. I've had the secondary and primary sensors changed at least 4 or 5 times already. I've learned to ignore it when it comes on now, and it goes away after a 1000 miles or so. I usually get the CEL when it's hot as hell outside. I think it's the F.I. HFC's or my uprev tune causing it.

Last night I cleaned my MAFs. Thy looked ok, but I assume that even a slight film would cause a problem. Also cleaned my K & N's and made sure they weren't putting out any excess oil. Also looked for exhaust leaks and checked the intakes & everything looked good. Haven't reset the codes yet, but I did do a 10 mile highway drive this morning and mileage seems normal - about 28 MPG. I'll get my code reader on Monday and clear them and see if they come back.

Just an update. Stopped by the dealer on Friday and they cleared my codes and said that it may not have been anything since it threw both banks at once, but wasn't uncommon to see them with HFCs. So far, they haven't come back.

Funny story, since it became cold here in Houston, <70 F, I found a mouse nest in my 4runners airbox. This caused my cel light to come on, maf dirty from paper element.

thousand oaks nissan just replaced my o2 sensor last month under warranty. i would try the same

Code reader at Costco for 89 dollars.Its dummy proof and resets the code with ease. I use this on my other cars as well.
I have test pipes and it annoys me to see my check engine light all of the time. If you dont like it for any reason, they will always take it back

Im having the same issue, I just put on my FI HFCs (Friday) and I threw a code.. Hopefully I can figure it out, I did take it to the dealer, and they wanted to charge me to fix it, I was like fvck that.. I'll fix it myself. haha.

:tup: good call on fixing it your self, hopefully it is just not seated 100% or something minor.


When I did my TP's I had no issues, but I know others have had them after TP's or HFC's from not having the gasket seated proper or not even one in there at all.

eastwest - yours had bungs right?

Yeah, mine had the j bungs..and the gaskets were on there correctly.