# Service Engine Soon Light - For What It's Worth



## JBW857 (Aug 17, 2005)

My SES light has been on for several months. I didn't worry too much earlier this summer when it started to come on and stay on. However, as October approached (the month my '01 Frontier gets inspected), I started to worry. No inspection stations will inspect the vehicle if the SES light is on.

I read all of the information on this site related to the codes wrt the SES light. I went to Autozone and he determined that the code was "P0420" which relates to plugs, injectors, O2 sensor and catalytic convertor. I was going to spend some money on the small parts first. However, before I bought the parts, we had a cool front blow in to the Houston region during the day while I was at work. Believe it or not, when I started my engine, the SES light did NOT come on. I drove home (30 miles, 45 minutes) and the light never came on. 

The next day I went to have my Frontier inspected. The light was still off. It passed. Later during the day, the outside ambient temperature started to rise. The SES light came back on! Is this a temperature-related phenomenon?
The truck passed inspection, so I'm happy.

One fix that the Autozone rep gave me was to disconnect the battery for a few minutes. This resets the engine computer and will turn off the light.


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## deathtorice (Jun 29, 2005)

http://www.obd-codes.com/trouble_codes/generic/p0420-catalyst-efficiency-below-threshold-bank-1.php

try those things. how many miles are on the truck?


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## JBW857 (Aug 17, 2005)

*Reply*



deathtorice said:


> http://www.obd-codes.com/trouble_codes/generic/p0420-catalyst-efficiency-below-threshold-bank-1.php
> 
> try those things. how many miles are on the truck?


I plan to change the cheap items first. There are only about 73,500 miles on the truck.


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## 98FrontiSE (Nov 6, 2004)

I have a similar problem with my Frontier. Everytime it rains, it will chug and the check engine light will come on. All I do is disconnect the battery for about five minutes, then hook it back up, that should reset the computer and you should be good to go, it has ALWAYS worked for me.


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## JBW857 (Aug 17, 2005)

98FrontiSE said:


> I have a similar problem with my Frontier. Everytime it rains, it will chug and the check engine light will come on. All I do is disconnect the battery for about five minutes, then hook it back up, that should reset the computer and you should be good to go, it has ALWAYS worked for me.


Thanks for the info. I will keep this in mind in 12 months when I have to get my truck inspected. I don't want to spend big bucks on repair just to have my truck inspected for something that is probably very minor!


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## azrocketman (Oct 5, 2005)

*Service engine light*



JBW857 said:


> Thanks for the info. I will keep this in mind in 12 months when I have to get my truck inspected. I don't want to spend big bucks on repair just to have my truck inspected for something that is probably very minor!


Check with your Nissan dealer. I believe that there is a technical service bulletin to revise the computer software that answers this problem.


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## ethiosew1 (Apr 13, 2009)

My car shows "service Engine Soon" sign whenever I start the car. What is the problem with my car? Please help me


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## azrocketman (Oct 5, 2005)

The On Board Diagnostics Version 2 (OBD II) system has detected a malfuntion. Before anybody can offer advice the OBD II needs to be interrogated to determine the malfunction code. A code reader costs around $60.00 to $100.00. Some parts stores, e.g. Checker, will read the code for free. Write back when you know the malfuntion code.

Steve


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## paulaAZ (Jul 16, 2009)

*2001 Altima SES light*

My SES light came on this afternoon when I was leaving a meeting. I just had the battery replaced about 1-1/2 weeks ago and filled up with gas yesterday. I did loosen and retighten the gas cap but did not drive that far after doing that. I'm due for an oil change and maybe at 3,500 miles since the last one. Any ideas?


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## azrocketman (Oct 5, 2005)

The SES light operation is independent of the oil change interval. I'm not sure of the conditions that the OBD II uses to check the fuel evaporation system but a short drive with a full tank may not be sufficient to reset the SES light.

What you really need to do is have the OBD II read to determine the OBD II code. Some auto parts stores will read the code for you. Once you know the code post the information (preferably on the Altima forum since there may be problems/cures unique to that chassis and powertrain packaging). The information will allow responses directed at the code.

Steve


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## paulaAZ (Jul 16, 2009)

Steve -- Thank you so much. I actually had to go out to a friend's house yesterday after work which was quite a drive and when I got in my car to come home, the SES light had gone off. Loosening and retightening the gas cap must have done it. I'm usually careful about that b/c I have read that the SES light will come on because of it. Again, thanks for your advice and input.

Paula


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