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Checking Codes=Pointless


Channel595
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well every one here always says "check codes" first part of trouble shooting... in most cases i would agree but these engines are so old that they only have about 15 codes and only tell you if you have a shorted or "implausable" signal from a sensor. the codes will not tell you if a sensor is intrrmittent or if it is not working properly. just my 2 cents.

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yea but it gives you a baseline of where to start looking for issues, you could always just start randomly throwing parts at it "thinking" you know the problem with 0 direction. Might get a bit expensive but it IS smarter than doeing something that only costs you a couple minutes of your time :FartExplode-vi:

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if you have 15 codes stored in your system, then you should either look at the codes and see which ones pertain to the symptom you are experiencing. If any or all of them could be causing it, then most likely what has haappened is one part or one system has malfunctioned, and a cascade of failures have occoured becuse the first system isn't working.

 

If you've got a bad hiccup, or lag in acceleration for example, driving it like that can cause codes in the transmission computer for hard shift. It's no that there's anything wrong in the transmission, it's just a concequence of the original failure.

 

Sometimes the only way to diagnose it properly is to completely clear all the codes, and then drive it untill the first code comes up, and that will tell you what system, or "circuit" you're looking at.

 

you are correct that the code doens't tell you what's wrong, but if you've got a running problem, and the code is for an o2 sensor, starting by replacing plugs, cap rotor and wires will just waste your money, and you'll still have the problem with the o2 sensor.

 

The code tells you what system is causing the failure, then you have to test the components in that system to find the failure.

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Even though the system isn't as informative or convenient as OBD2, it can still point you in a specific direction and I'll happily take any info/hint I can get. In conjunction with the FSM and it's descriptions on troubleshooting malfunctioning components, it is usually enough to narrow things down quickly.

 

B

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OBD-II can be just the opposite of OBD-I, too much information. It will register cascading failures and lead you to believe (or be told...) that you need to replace 6 different things when there is actually one failure causing the other 5.

Edited by Alkorahil
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OBD-II can be just the opposite of OBD-I, too much information. It will register cascading failures and lead you to believe (or be told...) that you need to replace 6 different things when there is actually one failure causing the other 5.

Agreed, but so can the WD21 OBD1. I've seen quite a few people here with a string of codes too, but usually not more than 3 or 4

 

P0442, EVAP sys small leak detected! Awsome obdII CEL code! Dont forget your gas cap!

Yep, the wife's Matrix came home with a CEL one day so I grabbed the reader, headed out and got that. Cleared it, opened the gas hatch, unscrewed the gas cap, screwed it back in, shut it and told the wife 'tell me if it comes back tomorrow'. It didn't and she thinks I'm a genius... :rolleyes:

 

My ma's JGC throws a code constantly (knock sensor and vacuum leaks or whatever)

 

 

$98 every time she takes it in...

 

 

I'll take my ecu ANY day

What year is it?? No diagnostics what so ever?? Sell it and get something that doesn't have stone wheels?? :shrug:

 

B

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My ma's JGC throws a code constantly (knock sensor and vacuum leaks or whatever)

 

 

$98 every time she takes it in...

 

 

I'll take my ecu ANY day

 

Chryslers with digital odometer will give you the codes. Turn key off and on like three times and the codes pop up in the odometer

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  • 4 weeks later...

Amen to Nissan for making the ECU's easy to get to. IF it wasn't for those easily accessable & the codes, I'd been spending lots of money over the years on both my Pathy's. I truely love the ECU's & codes. I've helped a few fello Pathy pals out with the codes. LIke most are saying, it gives you a general idea/system to start looking for your issues. Not very many other vehicles out there that has this system, unless you go out & buy a code reading system or take it to the shop.

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