Re: S70 Check Engine Light

  • Thread starter Thread starter Mike F
  • Start date Start date
M

Mike F

Michael said:
Grrr, my light came on after I parked my car after lunch. Half a year
ago, it came on due to a thermostat problem, and now it's back on again!

Could this possibly have anything due to the fact that I was driving on a
close to empty tank this weekend? It's a 1998 S70 T5 with 59K miles.

Once the light is tripped, will it stay on til reset, even if it came on
for some fluky reason? Any way to reset it manually?

Mike

Not likely. If the fuel level gets so low that air bubbles get into the
fuel line, the check engine light can come on, but once the tank has
been refilled the problem goes away.

The light was not on when you turned your car off, and came on
immediately after starting?

Go to Autozone or similar, they will read your codes and reset them for
free. Make a note of all codes for reference. If you have a problem it
will be back.
 
The light came on right around when I was about to park my car in the
parking garage after lunch yesterday. It was on when I went home, and
it'll likely be on when I go to work in the next 10 minutes.

I'm going to try to reset it as someone had suggested.

I'll try autozone later if it comes back on. Thanks for that tip. I
didn't know anyone would do that for free!

Mike
 
Michael said:
I took the car to Auto Zone tonight, and sure enough they read my OBD for
me. P0172 ... something about the system being too rich.

So, does this have a wide range of possible problems, like oxygen sensor,
vacuum leak, air mass meter, something clogged, etc?? As I mentioned in
my first post, four days before the light came on, I was driving on a
very, very low tank of gas. Could some deposits in the bottom of the gas
tank have gotten into something to cause further problems? If it helps, I
had my car's 60K maintenance done almost exactly 2 months ago.

Any suggestions for my next course of action?

Mike

This is equivalent to Volvo's codes 2-3-1 or 2-3-2, long term fuel trim,
upper limit. This is basically the "vacuum leak" code. While it's
possible that the low fuel level caused this code, what I would do now
is look at the vacuum elbow for the PCV system that's on the end of the
intake manifold behind the power steering pump, and at the other elbows
under the throttle pulley cover. Follow as many of those line as you
can looking for breaks or disconnections. If you find a problem,
repair it, if not, continue driving the car and see if the problem comes
back.
 
Today, as I was driving around, I noticed that the Check Engine light
wasn't one anymore. It went off somtime today, but I don't really
remember when. I had the code read a few weeks ago at AutoZone, but I
didn't ask them to reset it.

Is it normal for the light to reset once the issue is resolved? I thought
that a reset was a manual thing and not an automatic thing. If it is not
supposed to go out on it's own, could this also mean that my dash has a
bad bulb? Bleh. That would be just another issue =(

Mike
 
Mike F said:
Yes that's what's supposed to happen. While you're driving along, the
computer runs a check on each component in turn. The whole check cycle
takes about 30 minutes, and then the process is repeated. Once the
check cycle is completed 3 times without the error present, the check
engine light goes out, but the code will still be stored. Once the
engine has completed 40 warmup cycles (start engine cold, run to fully
warm) then the code will be erased from memory.
Mike F, sorry for butting in, but you continually amaze me with your
knowledge of these cars, and I am always being amazed by what I think is
incredible sophistication of the engine management systems.

Stuart. (with a thick 740)
 
Drats .. unfortunately, later that day, the light came back on =(
 
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