Jump to content

Service engine soon light....


MTGunner
 Share

Recommended Posts

OK, service engine soon light on once again.Went to Autozone to have them read the code. No code came up. This occurred 3-4 weeks back and light extinguished after a few days. No issues running, no issues stopping, no issues period. But service engine soon lamp is on. The owners guide says take to dealer..

NO! Service is well up to date. ???? MTG

Link to comment
Share on other sites

4 hours ago, MTGunner said:

OK, service engine soon light on once again.Went to Autozone to have them read the code. No code came up. This occurred 3-4 weeks back and light extinguished after a few days. No issues running, no issues stopping, no issues period. But service engine soon lamp is on. The owners guide says take to dealer..

NO! Service is well up to date. ???? MTG

My 97 did the same thing. The light was on for not even kidding you 11 years (since it at the time it was my moms car and shes first owner) and then one day i fired it up and it went off and hasnt turned on since. Still have no clue what it was and why it went away but multiple shops tried and couldnt figure it out. If there truly is 0 things wrong with it then i wouldnt mind it but i would still try and get it fixed or just ask the dealer

Link to comment
Share on other sites

OK, so owners manual says when on constant could be an emissions problem. Did all the code research...NOTHING. Pathygig12 seems to have same issues. BTW, thanks for the help and input all.  I am going to put Lucas fuel cleaner in my fuel tank for next few fill ups. This should clean injectors, fuel tank, fuel lines and engine to some degree. Always had faith in Lucas products. In online reviews it states that when engine is clean burning it should clean catalytic converter. Not @bsolutely hanging my hopes on fuel system tho’. With hope this will help. MTG

Link to comment
Share on other sites

Forget the Owners Manual.  You need the Factory Service Manual: https://www.nicoclub.com/FSM/Pathfinder/2000_Pathfinder/

Specifically, get friendly with the Engine Control (EC) chapter: https://www.nicoclub.com/FSM/Pathfinder/2000_Pathfinder/ec.pdf

 

Codes can clear themselves depending on the "trip detection logic" and severity/type of code.  Not that it helps determine the code, of course, but I'd start with EC-54 and get familiar with the system.

 

Then jump to EC-70.  Have you tried putting the truck into diagnostic mode before?  The 01+ trucks use a sequence of pedal presses, but the 96-00 will use a small screw-potentiometer on the ECM itself.  On EC-72, that's the procedure to enter the diagnostic modes on the truck.  Even if there is no stored code, it flashes a code to indicate there are no stored codes, and then shutting it off resets the ECM.

 

The first thing I would check is that the diagnostic screw is rotated fully counter-clockwise.  If you attempt this, be careful as it can be fragile...use a small screwdriver with gentle turns...breaking it off isn't fun.  Then, follow the procedure to trigger any codes, which get flashed on the MIL light in a long-short pattern.  The FSM describes what to look for, and you can let it blink endlessly to ensure you've gotten all codes.  An "0505" (5x long + 5x short) code means there are no codes stored.

 

Notably, I've had identical symptoms to what you've described, but on my 98 Frontier: truck ran fine, but every now and then the MIL would be on for a while, then go off randomly, but never return any codes.  The reason I mentioned checking that the screw was fully counter-clockwise is because it needs to be in that position when not in diagnostic mode.  Otherwise, I think it can leave the ECM in a diagnostic mode that monitors the O2 sensors.  My situation is only unique in the sense that I had accidentally damaged the diagnostic screw and ended up soldering in a different style of potentiometer, and then eventually forgot which direction had become CC and CCW.  As such, for years the ECM wasn't ready.  I hadn't realized I had the rotation backwards until I needed to get it emissions tested and realized that none of the truck's emissions systems were ready despite years of driving.  Ooops.

Edited by hawairish
  • Like 1
Link to comment
Share on other sites

6 hours ago, Slartibartfast said:

That's funny. I didn't know the WD21's blinking light engine diagnostics continued into the R50.


Honestly, I didn’t either, but that’s what the FSM showed. I was originally going to describe the pedal procedure. 

Link to comment
Share on other sites

Get a Bluetooth OBD2 reader and download a free scantool app for your phone. The readers are super cheap and will give you very easy access to the issues that pop up. This one is only $11 on Amazon and there are far better ones for more money but if you just need to read codes these work fine. It will allow you to scan the ECU with your phone app the moment the code comes up and provide a basic description of the issue. 

 

https://www.amazon.com/dp/B00PJPHEBO/ref=cm_sw_r_other_apa_i_N4fdEbY1YYENZ

 

I have something similar and have had great success using it on multiple vehicles for that past 6 years to read and reset the Check engine light error codes as well as get live data streams on various sensors.

 

I'd wager it has something to do with your O2 sensors (common issue with the 01+ 3.5 rigs). The check engine light will come on and off intermittently without driveability issues. Nissan put out a TSB for dealers to reflash the ECU and fix the constant O2 sensor problem, related to the time required to reach operating tempature I think, but I've never known anyone to do it. Just heard stories.

 

Check for a broken shoelace sized woven metal grounding strap on the passenger side exhaust pipe, close to the catalytic converter. Very easy to spot. Should go from the pipe to the heat shielding. Not all rigs came with them but I believe most early 01's like mine did.

 

A running theory is that they break and cause these prolonged intermittent Check Engine lights to pop up but there isnt a whole lot of evidence to back that up as it appears the newer rigs with similar proplems never had them. Some, inclduing myself, have had the O2 issue resolved by replacing this broken exhaust grounding strap.

Link to comment
Share on other sites

.....I'd wager it has something to do with your O2 sensors (common issue with the 01+ 3.5 rigs). The check engine light will come on and off intermittently without driveability issues. Nissan put out a TSB for dealers to reflash the ECU and fix the constant O2 sensor problem, related to the time required to reach operating tempature I think, but I've never known anyone to do it. Just heard stories.......

Ditto on literally ALL of this post!

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...