Nissan-related question...

[TeeCat]

Hey, all...

I have a non-MC mechanical question. I thought I'd ask here because of the breadth of mechanical knowledge and experience, and this issue may not be at all uncommon among you.

I have an '02 Xterra that I love. About 104,000 miles, no mods. Recently, it was becoming increasingly obvious that the muffler and adjoining pipes (original) needed attention, so I had OEM replacements installed, basically from the cats rearward. I had the work done at a local Midas, where the work and customer care has been excellent.

Right after that - the same day on the way home - I got a Service Engine Soon (SES) light that I'd never had before. The truck would not go beyond 2500 rpm, so I went back, and it was discovered that the tech had simply forgotten to plug in the mass air sensor after the courtesy check. No biggie.

I'm still getting the light intermittently, though, and I used Advance Auto's scanner the other day. It shows 4 codes - actually 2, but each one twice. One's for the knock sensor and the other's for the O2 sensor on the right bank. The knock sensor is below the intake manifold and I'm not even going there. The O2 sensor is easily accessible to someone with a lift, stands, etc., I suppose.

So, basically, I find this timing interesting since it's coincident with a new exhaust. Could I have a bad right bank sensor, or could the work and the new exhaust envoronment simply have "confused" or "upset" the computer? The truck seems to be running as well as ever - quiet too - and I can't throw any more money at it right now.

Thoughts appreciated!

TC

 

[Visegrippe]

Tryto clear thecodes by leaving the batt disonnected. No mafsignal probablysent themachineinto limp mode, which mmight have fouldthe sensors, I would imagine they're okay, though. Basically leqavethe batt disconnected overnight, orlonger. Itwill force the computer to relearnthe engine.

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[TeeCat]

No mafsignal probablysent themachineinto limp mode

Aaaaaah... that would seem to make sense, as that was the "trigger" event, seemingly! Vice, thank you. I cleared the codes using that option on the scanner. Would that have the same effect, or do I have to disconnect the battery to get the computer to relearn the engine? I have not tried that yet.

 

[Visegrippe]

clearing the codes just clears the codes, there's not really any shortcut to reset the computer. some people disconnect the battery then touch the cables together (not recommended!) to drain the residual charge.

8-12 hours is recommended. you will loose your radio presets.

i have a g35 and there are many owners who make a regular habit of reseting the computer because it tends to adapt the transmission to your driving style, and most people can't drive hard enough to keep it nice and crisp, so it goes into "granny mode". it will clear your codes and will reset the comp to its default program.

no guarantee it will cure the problem, but there's a good chance it might.

 

[TeeCat]

Aaaaah... got ya. I need to interrupt the power supply completely.

Okay, thanks! Hey... it might work, and it's free! I'll try it!

 

[Travis]

Visegrippe, I havea helloftime reading yourposts fromyour phone!!!

 

[Tech7]

Nope, no limp mode on Nissans. The knock sensor code is common on the x terra. It however, will not illuminate the SES light, just stores in memory. The fix is a new updated knock sensor. (stupid expensive too. It will not cause ANY drivability problems) There is a technical service bulletin on this. I usually replace them when the intake gaskets need replacing for coolant leaks. As far as your 02 sensor code on bank 2, I could give more info if you gave me the generic code P0.... sensor 1 or sensor 2. Sometimes what happens when exhaust is replaced is that the tech will use an air hammer on the pipes and it kills the heater in the sensor from the vibration. They are fairly sensitive and yours does have 100K on it. It just happens. Most likely a post cat sensor. Like I said, could tell you more with the generic code. Oh and you never need to leave your battery disconnected for 12 hours. Ever.

 

[TeeCat]

Tech, the battery's disconnected now, and it's bedtime, so I'll just re-connect it in the morning.

The code for the O2 (Manufacturer Controlled Fuel Air Metering?) is P1143. The KS one is P0328. The O2 one must be what's illuminating the SES. They are the codes that showed up on the reader... said 4 codes, but there were only two numbers.

Thanks for this!

TC

 

[TeeCat]

Guys, just an update:

I tried the battery trick - it's free and couldn't hurt anything - and the light's been off and stayed off since Saturday morning when I reconnected it. So, I'm cautiously optimistic that the theory about the lack of a mass airflow sensor signal having upset the computer was correct.

Fingers crossed...

TC

 

[Tech7]

Tee Cat- P1143- system lean bank 1. If your light stays out-cool. But if it should come back on, there is technical servive bulletin for you truck. It involves installing an additional ground for the 02 sensors. There is a subharness available from Nissan. Sorry about getting back to you so late, I forgot. Let me know if I can be of any more help.

 

[TeeCat]

Tech, thanks much... I'll remember this, and hopefully this thread. But that light's still out! It'll be a week tomorrow morning! Maybe the computer was just confused...

TC

 

[Tech7]

Oh good, I hope you have no more problems. The X-Terra is a pretty reliable truck, but all cars have quirks now and again. Like I said, just let me know, and I'll do what I can to help.

 

[TeeCat]

Well, Tech, thanks for this. Sadly, almost no sooner did I see your note than, after a week, the light's back on. Rats. I suppose I'll have to take it to a dealership when I get a chance, but I'll be taking your information with me, for sure!

Crap... thought I was done with that issue.

 

[Tech7]

Figures. Let me know what they find.