Aftermarket Exhaust Installed & Service Engine Light Came on
 

On Saturday I installed a slightly used OEM Nismo CBE on my Z. I bought it from one of the other members on here. It only has around 2000 miles on it and looks brand new. Installation was a cinch. Took only about 35 minutes. After the install I drove the car for over an hour from Virginia to Baltimore with no problems. On Sunday I went for a 5 minute drive and the Service Engine Soon light came on. It came on and stayed on. When I got back to my house I remembered I forgot to reset the computer after the CBE install, so I disconnected the negative battery terminal and depressed the brake pedal to drain whatever was left in the system. After about a minute I reattached the cable. When I started the car the light was off. I figured, Problem solved! Wrong.

Today I went for a drive and within in 5 minutes the light came back on. I honestly can’t see how a stock Nismo CBE would cause this issue. I only disconnected the battery for about a minute. Should I do this for a longer period of time? I’m afraid if I bring it to the dealership they are going to give me a hard time about the mod. My Z only has 2075 miles on it and I haven’t done any other mods. I also read the owner’s manual and it said to check the gas cap. I did and it was on tight.

Any suggestions or thoughts on this?

chances are it's not the exhaust causing the problem.... just happened to throw a code after the install of the new exhaust. Read the code and then you will know. Or change out the exhaust to stock and see if it goes away... but it is possible you have another problem

Well that would be a big coincidence. Any where I can take the car to find out the code, other then the dealership?

I would check and re-torque all exhaust connections, I would assume any decent local mechanic can check the code for you.

Autozone will check codes for free, but they won't clear codes.

Out of curiosity, how would an exhaust leak in a CBE throw a code? The CBE is after the O2 sensors, so how would it detect this? A loss in back pressure?

Agreed, there arent any sensors at all behind the cats, im willing to bet youre probably running a rich/lean condition and its probably triggering the code, throw some G3 intakes on it and maybe it'll balance out! Go to autozone and have them check the code and report back.

Are you taliking about the "Check Engine" light which indicates a fault, or the Service reminders in the left side pod?

If the latter it's just a coincidence. Re-set them to the proper mileage intervals per the Owners manual. If it is the CEL, then get the code read and correct the problem.

It's the "Service Engine Soon" light (CEL) in the center. It's not in reference to the service reminders. I'll go to AutoZone tomorrow and get the code.

I really think this Z is cursed. So little mileage and so many problems.

try leaving your battery neg cable off for more than a minute, try half an hour or longer if your not in a rush, then if it throws a code again you can get it read.....also if you used an impact gun or were rough with the bolts when taking off the stock exhaust you may have damaged the catalytic converter sensor = $$$

We were pretty careful to not touch the sensors. I'll disconnect the batter for at least 30 minutes tomorrow and then I'll take it for a ride. If it comes on, I'll head over to AutoZone to get the code. I'll post the results.

Thanks everyone!

I wouldn't bother with disconnecting the battery again. If the cel is on it is best to read the code and find out the exact cause.

:iagree: If the disconnect was long enough to reset the light then it reset everything. Just get the code read, takes 5 minutes.

Finally made it over to AutoZone. They said the light is on because there is an issue with the second O2 sensor in bank one. If I'm correct, that's the one on the driver's behind the cat. I guess I could have bumped it while doing the CBE install. I'll put it up on the floor jack tomorrow and check the connection. I've never messed with 02 sensors before, is there anything I should know or to look for?

Given that you have stock cats, it's either something you did to the sensor or you have a leak where the exhaust mates with the cats. Did you use new exhaust gaskets?

Yes and no. I used the stock gaskets that attach the CBE to the cats and the muffler, but used new gaskets in the middle section. since they had less then 2000 miles on them, I didn't think there would be an issue.

switch dem gaskets!

Out of curiosity, how can a gasket that is after the sensor effect It's reading?

Although the general flow is front to rear through the exhaust, it can move air in backwards a very short distance. Air is only being pushed down the exhaust during the exhaust strokes.

Also check that the wires on the O2 didn't get pushed against the exhaust.

Interesting.

If the wires are up against the exhaust, could they melt, or will that just effect the reading?

Tomorrow I'll run by the local dealership and get 2 gaskets. If I have time I'll install them and check the 02 connections.

Any other suggestion?

The wires could melt. Part of the wire where it comes out of the O2 is protected, the rest of it is not. Normally it's not at much risk because the harness is short enough to keep it out of trouble.

Hopefully the gaskets will do the trick.

Got the gaskets today at the dealership. $40 for two gaskets! Well hopefully this will fix my problem. I'll most likely install them next Monday when I have off from work.

Yep, gaskets make a world of difference lol. I had me CEL on for ages and ended up being that the gaskets had been leaking which caused air to get sucked in past the O2 sensor causing a lean condition...

Never would have thought gaskets would cause this, but hopefully that's all it is. After I install them should I reset the computer?

Well I replaced all of the gaskets and that had no effect. I took the Z in for an oil change today and had them look at it. They found that one of the 02 sensor’s wiring had been chewed on by some sort of small animal. I don’t garage my car, but I do cover it, and it sits for days on end, so I’m sure some little varmint took shelter under there and then made a snack out of the insulation. Little bastard. The dealership wants $190 for the part and $130 to install it. That’s highway robbery as far as I’m concerned. I have a friend who can do it for free, but I have to order the part. The service manager gave me a part number of: 26AO-ET000. I would like to try and order the part from an outside vendor, so I did a search for it on google, but came up with nothing. Anyone have any suggestions on where I can order this from, other then from the dealership?

Well I did tell you to check the sensor wires while you were under there :) Damn varmits.

Here's the rear sensor - $145 each!
370Z - Rear O2 Sensor

I actually did, well mostly. It wasn't easy to spot, but it's clearly two little teeth that made it.

Thanks so much for the part. Are both of the rear sensors identical?

Also, any suggestion son how I can prevent this in the future? Is wrapping the lines in electrical tape a bad idea?

Drive the car more :excited:

Lol. Just don't let it sit for too long. I had over $300 worth of damage to my from mice. Little bastards. You could also put a little bit of poison on the inside lip of the rims if it sits for a long time.

It sat a lot over the winter because of the 3+ feet of snow we got. It won't sit as much over the spring, summer and fall months, but it isn't my daily driver. I'm gonna put some traps/bait under it. I've had a lot of issues with cars over the years, but I never would have imagined this one!

Yes, both rear sensors are the same.

You can wrap the wires beyond the heat shielded part but I don't think that will do much to keep the varmints out. This was an unusually heavy winter for you guys down there, hopefully next winter you will get to drive it once in a while.

I was wondering if there was anything that rodents could get into underneath my car, and then I stumbled onto this thread. :shakes head: Putting some poison in the inside lip of the rims or under the car is a good idea. The wife and I carpool to work most days, so my Z ends up sitting in the driveway for a couple days at a time...

My truck has a bit of a cavity in the V between the cylinder heads, I'm always finding nut shells and fuzz left behind by critters. They haven't eaten anything AFAIK, but then again it is running like crap so maybe they did, LOL.

I have to say I think this is a poor design. I realize that you can't stop critters from eating what they want to eat, but these wires are only about a foot from the ground and are subject to being hit by road debris and the elements. A cheap plastic shroud could easily solve most of these issues.

You cant solder them for free?

The split is very close to the sensor. Not much to work with. I thought about that, but I don't think it's a possibility.

Give it a shot. What do you have to lose at this point? Even if you have enough to splice or twist and use electrical tape it will save you a few hundred dollars for now, maybe years.

True. I'll have some time next week to mess around with it. Worst case, I'll just have to spend $140 for a new one and have a friend of mine show me how to install it.

The rear sensor is very easy to replace (or remove for repair). Rent the O2 removal tool from Autozone or parts shop (usually free with deposit), run engine to warm up exhaust, shut off engine and spray liberally with PB Blaster and allow to cool to touch. Disconnect plug end of sensor and unscrew with rented tool. You don't have to use the tool but it does make things easier.

I didn't realize you needed a special tool. Do they unscrew?

The tool is entirely optional. At the base of each sensor you will see a typical hex nut in 7/8" size, and you can use a large 7/8" wrench to do the removal. The O2 sensor simply screws into a threaded socket on the pipe.