'99 Avensis 1.8. An orange warning light has lit permanently on the dash
panel. The manual say it is a "malfunction indicator lamp". It is orange and
the symbol is the shape of an engine. Everything in the car is working as it
should with no problem. The manual say it means there is a problem in the
engine electrical system somewhere. Any ideas? Is it serious?
Here in the States we have Parts Stores called AutoZone. When the MIL
lights, you can take it and they'll run a scan tool on it and read the
codes (they're often called P Codes, because most, if not all begin with
the letter P). Get the code, and Google Toyota Trouble Codes and it will
give you an indication what's wrong. For Example, P401 (which appers to be
the most common code) is: Oxygen Sensor, Low Vacuum, low EGR flow, and
another I can't recall. Being the master tech I am I threw two O2 sensors
in and then found out 7 months later it was a plugged vacuum hose!!!
See if you can find someone to read the code and report back! ;)
This is the exact right thing to do Scribe. Hopefully where you are there
is some kind of auto parts store that will read the codes for you in the
hopes that they will then be able to sell you the parts. Then come back
here for discussion.
If the engine seems to be running fine and the light is on solid,
the computer has spotted a fault somewhere and wants you to go get it
Some auto parts stores have the code readers and will loan it to you
free to pull the codes - because they want to sell you lots of parts
to fix any possible problem the computer is complaining about!
(Don't buy a new part just because the computer flags it - it may
not be that part, but something else in that system. The codes just
give you a symptom and a starting point for a proper mechanic's
It could be as simple as someone left the gasoline filler cap loose
or off, and the evaporative emissions system didn't pressurize for the
last two driving cycles.
If the MIL or "Check Engine Light" is blinking, that's bad - stop
and call the mechanic for advice and you may need to get it towed in.
(At a minimum, check all the fluid levels and have someone look for
--<< Bruce >>--
I looked about and the Carina E is the same engine and set up.
"The On Board Diagnostics (OBD) on the Carina is easy to use. It does
not require any specialist tools either. The procedures are as follows;
1. With the engine turned off, open the bonnet and open the cover of
the service socket marked 'Diagnosis' located near the nearside suspension.
2. Use a suitable piece of wire or a paper clip to link terminals marked
E1 and TE1 together. "
The Avensis has the service socket in the car, in the fuse box near the
steering wheel. The socket is different and appears unmarked. If I could
identify the terminals I could get the code counting the blinks of the
malfunction indicator lamp. As you say, even if I get it, it could mean
many things. Even the wiring is checked, so it could be a short somewhere.
I reset the ECU by taking the fuse out for a minimum of 10 seconds. It
I did notice an airflow detector that goes in the air filter, on the
filtered side, left out (left out on the last service). This means some
unfiltered air was entering the engine. I replaced it and still the light
is on, after a reset. What does this flow detector do? Is it important?
Was the flow detector being out the cause of the problem? Knock on effect?
It is just a piece of plastic with two wires on it.
All 1996 and later model year passenger vehicles sold in the U.S. have to
comply with the On Board Diagnostics generation II (OBD II) standard. If
the diagnostic connector under the driver's side of the dashboard looks like
this http://www.obdii.com/connector.html then it is OBD II and shorting
terminals E1 and Te1 will not work and you will need an OBD II scan tool to
You have to pull the EFI main fuse or use an OBD II scan tool to clear the
codes. The other method is to disconnect the battery cable, but you will
lose the battery pre-sets and clock.
If that is the only wired sensor on the filtered side of the air filter,
that is the Mass Air Flow Sensor and is very important and is likely the
cause of the check engine light. If the light does not go out after a few
days of driving and you do not have access to a scan tool, disconnect the
battery cable to turn off the light.
"Ray O" <rokigawaATtristarassociatesDOTcom> wrote in message
What does the mass air flow sensor actually do? You say after a few days of
driving, then if the light is still on, disconnect the battery. Is removing
the fuse for the ecu the same thing? That will disconnect the power supply,
or will it? Disconnecting the battery. Will that upset the alarm and
central locking? Will that need to be reset?
Would a hole 1/4" round allowing unfiltered air into the engine do any real
The mass air flow (MAF) sensor tells the engine's electronic control module
(ECM) how much air is entering the engine so the ECM can determine how much
fuel to inject.
Some sensor failures have 2 trip detection logic. The ECM has a specific
definition of a trip, where coolant temperature has to get to a certain
point, engine speed and road speed have to be a certain amount for a certain
length of time, etc. With 2 trip detection logic, if the signal from the
sensor to the ECM has is outside the values the computer expects to see for
2 consecutive trips, the check engine light will come on and conversely, if
the ECM does not see a problem for 2 consecutive trips, it will turn off the
check engine light.
The MAF sensor has 2 trip detection logic, which is why I said to give it a
few days of driving. If you remove the fuse for the ECU (a.k.a. ECM) it
should clear the trouble codes in the ECM. Disconnecting the battery should
not upset the alarm and central locking but it may upset your factory radio
if you have an anti-theft code stored in it.
Pulling the EFI main fuse is the best solution if you do not have an OBD II
code scanner, disconnecting the battery is kind of a last resort if you
cannot find the correct fuse.
There are a couple of problems that can arise. If the hole is between the
MAF and the throttle body, then more air is entering the engine than the MAF
told the ECM, so the air/fuel mixture could be too lean, and if it is too
lean, you can get engine misfires which can ruin the engine and catalytic
converter and increase engine emissions.
Unfiltered air will contaminate the engine oil more quickly and will wear
the engine more quickly, which is why the intake is designed to have air
pass through an air filter first.
Finally, a remote possibility, depending on where the hole is located, is
that water can splash or get sucked into the intake. Water does not
compress, so if the volume of water that enters a cylinder is greater than
the volume of the combustion chamber, the engine will destroy itself. If
you want to know how much water it would take to ruin an engine, on a 4
cylinder 2 liter engine, each cylinder displaces roughly .5 liters. To make
the math easy, we'll say that the piston travels through .75 of the
displacement and the combustion chamber's size is .25 of the displacement at
top dead center. So if more than 125 Ml (.5 liters x .25) enters a
cylinder, the engine will be ruined.
"Ray O" <rokigawaATtristarassociatesDOTcom> wrote in message
Ray, the MAF was not in its hole, which is a rubber grommet. the hole is
about 1/4" size. The MAF was hanging outside.
I'll see if this light goes out in the next few days, then if not pull the
fuse again and see. The performance is fine and the fuel economy is normal.
What does the MAF actually do? Just a piece of plastic to me.
The MIL probably came on because air volume did not match throttle opening.
The MAF sensor has a tube that sticks into the air flowing to the throttle
body, and inside the tube is a very thin wire. Current flowing through the
wire heats it up, much like the resistance heater wires in a toaster or hair
drier, and the computer knows what voltage coming out of the wire should be
when the engine is idling. As air flows past the tube, it cools the wire,
resistance goes down and voltage goes up. Be monitoring the increase in
voltage, the computer infers how much air is flowing into the engine.
I thought they went to OBD-II computers worldwide by 1999 Model
Year, but that page describes the "older" computer system with the
"Jump T and E1, watch the blinking light" system. Could be, after all
you're somewhere in Olde England...
Look under the steering column in the drivers' compartment, by your
knees. They tuck the OBD-II connector right there.
Sorry, that one I have no idea. If it was the main airflow sensor
for the fuel injection the car won't run worth a darn without that
signal. If it is simply for sensing incoming air temperature it'll
still work (sort of) even if it's sitting in the corner of the airbox.
--<< Bruce >>--
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