# Misfire and O2 sensor



## Intechdo (Oct 27, 2017)

Greetings! 

I have a bit of a problem with my Nissan xtrail. I had it for about 1.5 years now and my engine light came on about 7 months ago. Didn't think much of it but had it checked out. P0132 which is the O2 sensor. No big deal. Then I noticed it misfiring. Start up is fine never had problems. The misfire is at it's worse in the morning and goes away after about 10-15 mins of road time. It's pretty bad. Some times really bad. Feels like the car is trying to drive on 2 cylinders. 

I had all my sparkplugs checked. I even went to the junkyard and replaced all my ignition coils. It's got better for a week and now is back at it again. What could be causing this? 

(I'm not by all means techy, so please dumb things down for me  

Nissan xtrail LE
2006
Manual transmission
2.5 I think?


----------



## quadraria10 (Jul 6, 2010)

I am sorry but I hope you realize that driving for 7 months with a bad O2 sensor has caused other damage. In addition to bad gas mileage its probably harmed your catalytic converter. Clogged cat could explain some of your symptoms. Sounds like you should have a mechanic give it an inspection and diagnosis. Just to point out, for anyone else with such issues, replacing a defective o2 sensor is relatively cheap. Having to replace your front cat ( which should also require new o2 sensors) will be much costlier. Good luck with it.


----------



## Intechdo (Oct 27, 2017)

Well dang. I went to see a mechanic regarding the engine light he said that O2 sensor is not a pressing issue. So I didn't do anything about it. (I also didn't have $150 to fix it at the time). 

Clearly he was wrong. Thanks for a quick reply.


----------



## MikeHJ (Mar 7, 2017)

The o2 sensors basically control the air/fuel mix by monitoring the o2 levels before and after the cat converter. The computer compares the two readings and adjusts the mix accordingly. Obviously, if one of the sensors goes bad, there's no way the computer will ever be able to adjust correctly.

If the mix is too rich, the cat can get fouled with unburned hydrocarbons. If too lean, then the exhaust gases get too hot and the inside of the cat can melt and clog the air flow.

First thing you need to do is check the tailpipe to see if you have good exhaust outflow. Compare to another car if you're unsure how strong it should be.

If it is strong, then change the sensor and hope for the best. If there isn't good flow, prepare to replace the cat and the sensors.


----------



## Intechdo (Oct 27, 2017)

So there has been some development. I took the car to a Nissan dealership. They ran basic diagnostics and told me pretty much what I knew already. There is no misfire code, there is no code for a failing catalystic converter. The O2 sensor number 1 is still showing up. Apparently it could be sensor number 2 that's faulty but it's the sensor 1 giving a code. In a nutshell if I replace O2 #1 there is no guarantee that's it's not the wiring or the O2 #2 and no guarantee it will get rid of the mystical misfire.


----------



## MikeHJ (Mar 7, 2017)

Intechdo said:


> In a nutshell if I replace O2 #1 there is no guarantee that's it's not the wiring or the O2 #2 and no guarantee it will get rid of the mystical misfire.


There are no guarantees, ever.

The misfire may be unrelated to the O2 sensor, but you've had a code for 7 months and NOW you have a misfire? 

It would be odd that the sensor giving the code is good and the sensor not giving a code is bad and diagnosis problem is a matter of eliminating variables

So....


----------

