'92 240 Check Engine Light

[L.D.Cosby]

Hi

I have a '92 240 GL that keeps giving me a 2-1-2 code on my computer and
turns on the check engine light. I changed the oxygen sensor and the light
came on again. Thought maybe it was a fluke, so I reset the codes and drove
for a couple days. It came back on. Anybody have any suggestions where to go
now.
Thanks
Larry

 

[brackenburn]

Hi Larry,

The info I have suggests that with a 2-1-2 code, the cause of the fault is
more a "wiring fault to the heated O2S sensor".
Perhaps you should check or replace the wiring.
Incidentally, what symptoms do you experience when driving the car? Has the
fuel consumption risen?

Good Luck.
Andy I.


| Hi
|
| I have a '92 240 GL that keeps giving me a 2-1-2 code on my computer and
| turns on the check engine light. I changed the oxygen sensor and the light
| came on again. Thought maybe it was a fluke, so I reset the codes and
drove
| for a couple days. It came back on. Anybody have any suggestions where to
go
| now.
| Thanks
| Larry
|
|

 

[Mike F]

Hi

I have a '92 240 GL that keeps giving me a 2-1-2 code on my computer and
turns on the check engine light. I changed the oxygen sensor and the light
came on again. Thought maybe it was a fluke, so I reset the codes and drove
for a couple days. It came back on. Anybody have any suggestions where to go
now.
Thanks
Larry

This code means that the computer is not happy with the signal (i.e.
signal voltage is too high or low) from the oxygen sensor. Since a new
sensor hasn't fixed the problem, then just about the only other problem
can be a bad connection. My guess is you have a problem with the sensor
ground. Measure the voltage between various ground points and the
battery negative terminal. Check all the ground wires, especially the
one from the back of the valve cover and firewall, but don't ignore the
connection from the negative cable and engine block, or even the
connections at the battery. And it's even possible that the exhaust
system has become electrically isolated from the engine and you may need
to run a ground wire directly to the oxygen sensor body. Later cars
have a signal ground wire built into the oxygen sensor that is connected
to the computer, just because of this problem. And just to make it
interesting, the problem may be intermittent, making it much harder to
find.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

[L.D.Cosby]

This code means that the computer is not happy with the signal (i.e.
signal voltage is too high or low) from the oxygen sensor. Since a new
sensor hasn't fixed the problem, then just about the only other problem
can be a bad connection. My guess is you have a problem with the sensor
ground. Measure the voltage between various ground points and the
battery negative terminal. Check all the ground wires, especially the
one from the back of the valve cover and firewall, but don't ignore the
connection from the negative cable and engine block, or even the
connections at the battery. And it's even possible that the exhaust
system has become electrically isolated from the engine and you may need
to run a ground wire directly to the oxygen sensor body. Later cars
have a signal ground wire built into the oxygen sensor that is connected
to the computer, just because of this problem. And just to make it
interesting, the problem may be intermittent, making it much harder to
find.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

Thanks everyone for the info. I'll try cleaning the battery connections and
the ground connections this weekend and see if that helps.
Larry