Geza

Hello,

The "Check Engine" light never goes on in my 88' Maxima SE 5spd except before I start the engine. My car has close to 190000 original miles in it, I bought it with 80000 miles in 1995. I have not replaced the oxigen sensor since I got the car (110000 miles ago).

My question is:
Can I assume, that if the "Check Engine" light only lits up when I start the engine, but other than that it's always off, that everything is fine with the engine and all of its electronic components, or there could be faulty parts in it (for e.g. the oxigen sensor), but you could only detect it if you run the diagnostics tests on the E.C.U.? (that's under the passanger seat in my car.)

My only problem with the car, that I used to get 25mpg on freeways, now I get 21-23mpg.

I have been maintaing the car regularly (castrol syntetic oil+filter, air, fuel filter, spark plugs, rotor+cap when they're needed, Techron every 6000 miles, etc, etc.)

So, I am getting amazed, that the current oxigen sensor has already more than 100000 miles and it hasn't failed or at least has not triggered the "check engine" light. (for some reason, I never got the periodic 30000 mile check engine light at all that's mentioned in the service manual.)

So, what do you guys think?

Geza

MaxWgn

iTrader: (1)

the light was probably disconnected, rather than reset, the last time it went on. This is factory procedure, and is even labeled as such right on the wire itself.

Geza

Do you mean, that the check engine light is disconnected from the computer but not the starting circuit?
Do you know why is disconnecting the light is a factory procedure? (were some folks annoyed by it?)

So, this means, that the check engine light has no alarm or diagnostics feature at all?

Would you tell me, where is the most common location where they disconnect the check engine light?

Thanks,
Geza

MaxWgn

iTrader: (1)

Correct...the light is lit by the ECU startup diagnostics now...other than that, it is strictly operated by the odometer. Should have gone off at 30k, 60k, and 90k miles...then, the wire has a quick disconnect, with a flag type lable, instructing to disconnect at the 90k check time. It doesn't really check or detect anything at all. It's just set to go off when the car reaches certain milage points, to make most people thing they need service, so the O2 sensor would be checked, and replaced if needed.

Geza

MaxWgn,
Thanks for your reply, it was very helpfule, now I guess, I will have to run some diags on the E.C.U. to see if the system is OK.
It's soo stupid to call that check light "Check Engine Light" when its only function ever was to remind about checking the Oxigen sensor and it never had enything to do with checking the whole engine like it does on many other cars.
Thanks again,
Geza