Fault code question

My wife's 1993 240 wagon's "check engine" light came on in below-zero
cold weather a couple of days ago. The local mechanic checked the codes
and found a 3-2-2. He cleaned the wiring harness contacts for the AMM
and cleared the codes. He said if the light came back on, he'd replace
the AMM and its wiring harness for no extra labor costs.

Today after driving around to run errands, the "check engine" light came
back on when she restarted the car. When she got home I checked the
codes myself. The ECU gave me two codes: 3-2-2 and 1-1-3. This
appears to be a AMM burn-off signal fault and also that the engine is
running lean. I reset the codes, but figure that something will need to
be done.

Am I looking at replacing the AMM as a certainty? Should I be looking
at something else? Is this a cold weather artifact or is it just a
coincidence that the light came on during the coldest weather of the
season? FWIW I'll have to replace the air box thermostat and lube the
flapper hinge too, I have no idea if that has ever been replaced.

I can easily replace the AMM myself, of course. I've never tried
replacing its wiring harness and don't yet know what's involved with
that. FWIW I have no garage and we'll be having below-zero to zero (F)
temps over the weekend, so I don't relish being out under the hood of
the car for very long! ;-) Fortunately I can bring the air box inside
to replace the thermostat!

Thanks!

 

Hi Tim,

We too have a '93 240 wagon (Classic edition). Had it since new.
I would first re-clean the AMM plug's pins and sockets *thoroughly* with
electrical contact cleaner, then apply dielectric grease and push and pull
the plug in and out ten times. ( If that seems a little weird do it anyway.
I got that from a Volvo technician .......)

You don't mention any drivability problems with the engine.

My info on Diagnostic Code 3-2-2 for the 240 LH2.4 Fuel Injection confirms
your "AMM burn-off signal fault", but the report (from brickboard.com) adds
that the cause is "a wiring break between FI terminal 8 and AMM #4". (I
feel that could still mean the AMM plug needs cleaning.) The report also
states that the symptoms are "various driving problems due to the dirty AMM
wire", and the Check Engine light does not come on for this fault

Re the 1-1-3 code, the Check Engine light does come on, and the fault is
"Fuel Trim (Lambda control) too lean OR RICH". The cause is "mixture
incorrect (duh!........); O2S wiring fault." The symptom is "high fuel
consumption".

Hope this is of some help.
Good Luck.
Andy I.



: My wife's 1993 240 wagon's "check engine" light came on in below-zero
: cold weather a couple of days ago. The local mechanic checked the codes
: and found a 3-2-2. He cleaned the wiring harness contacts for the AMM
: and cleared the codes. He said if the light came back on, he'd replace
: the AMM and its wiring harness for no extra labor costs.
:
: Today after driving around to run errands, the "check engine" light came
: back on when she restarted the car. When she got home I checked the
: codes myself. The ECU gave me two codes: 3-2-2 and 1-1-3. This
: appears to be a AMM burn-off signal fault and also that the engine is
: running lean. I reset the codes, but figure that something will need to
: be done.
:
: Am I looking at replacing the AMM as a certainty? Should I be looking
: at something else? Is this a cold weather artifact or is it just a
: coincidence that the light came on during the coldest weather of the
: season? FWIW I'll have to replace the air box thermostat and lube the
: flapper hinge too, I have no idea if that has ever been replaced.
:
: I can easily replace the AMM myself, of course. I've never tried
: replacing its wiring harness and don't yet know what's involved with
: that. FWIW I have no garage and we'll be having below-zero to zero (F)
: temps over the weekend, so I don't relish being out under the hood of
: the car for very long! ;-) Fortunately I can bring the air box inside
: to replace the thermostat!
:
: Thanks!

 

The 322 code does NOT set the check engine light. Something else caused it
to come on the first time and the mechanic either missed it or did not pull
enough codes. The no charge option could be an easy way to get you back
because he MAY know what is going on but can make more money on a new AMM
than fixing what is really wrong. ( Note: the last statement is from an
individual who treats everything as the sky is falling and everybody is out
to get me before the whole story has evolved.)

The 113 does set the check light. But, before spending any money, clean the
contacts to the AMM like Andy indicates...not too much effort and will do a
lot of good and no harm unless you break or bend something. See, the sky is
falling...:>)

AND then...there are two ten mm bolts with wires under them on the intake
manifold. Loosen them, clean them and retighten them. Also, clean the
battery terminals and be sure the wires to them are clean and tight.

Then clear your codes. If any codes return after the above cleaning, then
you should be concerned.

Those two bolts and wires provide ground for all the fuel control components
and are also the reference ground point for the Fuel Control Computer (ECU)
to "self diagnose" and set codes if something is wrong.

The manifold is aluminium, the wire's washer is some coated brass metal, and
the bolt is treated steel. Combine those three differences with electricity
and corrosion will occur if the connection is not tight all the time. With
the different metals, cold and heat extremes ( winter driving in a nutshell)
will loosen the contact enough to cause problems over time.

Every Vovlo Green Factory Service manual relating to fuel and emission
issues begins with a bold statement to Clean and verify grounds and
eliminate vacuum leaks prior to any testing of components.

Duane

PS. The time to clean those is just after a drive long enough to heat
things up under the hood. The residual heat helps keep your fingers warm in
the cold weather.

 

The mechanic cleaned the contacts. No dialectric grease, though. I
checked the contacts visually today and they looked OK, but you really
can't see into the female plug on the wire.

It runs fine so far. There is a problem with surging idle when cold,
but this has been present since she bought the car 2 1/4 years ago.
Replacing the fuel pressure regulator and (I think) the cold start valve
didn't fix the problem. The idle is fine when the car is hot and oddly
enough the idle evens out when she stands on the brake pedal.

I noticed that this fault code doesn't set the "check engine" light, so
I assume that the 1-1-3 must have done it. If the AMM is not burning
the crud off the wire, that might account for that.

She reports that her mileage is perhaps slightly less, but then it's
also been 15 degrees or colder for most of the last week. If the AMM is
crudded up, I suppose that could affect its function and cause the
engine to run rich or lean.

Thanks! I cleared the codes so we'll see if they come back, and
hopefully will get a break to be able to work on the car a bit. I'll
pick up some contact cleaner and dielectric grease.

 

Thanks, Duane!