A/F Sensor Heater Malfunction Code?

My pain in the butt 2002 Solara has been having slightly idling problems as of recently, but never threw a code until last night.

I have a long drive tonight and I was wondering if I now cannot make this drive because of this "A/F Sensor Heater Malfunction." I tried to understand what it was through googling it... I used a code reader and sort of understand cars but not well enough for this!

Any information is greatly appreciated. Thank you!

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  • 1 decade ago
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    A/F (air/fuel) sensor is another term for the O2 sensor, not a MAF sensor. If the code was for the MAF sensor, it would have said MAF sensor, not A/F sensor.

    All modern O2 sensors have a wire that supplies current to it to make it warm up faster, so that the system goes into closed loop (computer adjusts A/F ratio according to needs as measured by the O2 sensor) faster.

    These codes mean that you have a malfunction in the circuit that supplies this voltage that makes the O2 sensor warm up quicker and become operational.

    Usually this won't affect driveability, because the computer will run the engine off the pre-programmed values until the O2 sensor finally warms up. We're talking about the difference between less than a minute and 2 or 3 minutes here.

    There is the possibility though that your O2 sensor needs replacement simply because of age, and it could also be the cause of the code. If it's the original O2 sensor, and the car has over 100K miles, it probably needs replacing.

    If the O2 sensor were good other than the heater circuit, the engine should definitely run fine after it warms up from exhaust heat, the same way the early style ones did.

    But one that's contaminated from years of use becomes "lazy" and will give you idle problems due to not controlling the mixture properly after it's warmed up.

    This won't usually set a code by itself, but it may finally have gotten so bad it's affecting the heater circuit within the O2 sensor itself, triggering that code.

    EDIT *** Certainly O2 sensor is the more common term in American usage, but since when is a Solara considered a "domestic" car? It may have been built in America, but Toyota is still considered an import make, is it not?

    And when referring to MAF sensors, I guess you hadn't noticed that when it's spelled out in the long form, airflow is usually one word, and there is never a / between the A and the F in the acronym use of the term.

    http://www.aa1car.com/library/maf_sensors.htm

    http://www.aa1car.com/library/vaf_sensors.htm

    And yes, O2 sensors do measure oxygen content in the exhaust stream. This is used by the ECM/PCM to deduce the Air/Fuel ratio being introduced into the engine, and adjust it accordingly. Hence, the common use of the term A/F sensor to refer to them. Not technically accurate, but used by many professionals, including some of the automakers themselves, regardless.

    Considering the / between the A and the F, and the lack of an M or V or the like proceeding it, I think the logical conclusion is that it's referring to an O2 sensor.

    Besides, a problem with the circuit that heats the MAF (whether hot-wire or hot-film), would tend to affect more than just idle quality. It would also throw a code almost immediately.

    ________________________________________

    btw stinkbalm, I noticed your other question. It doesn't seem to be related to this problem, but I was wondering if you have a (digital/high impedance, not analog/low impedance) voltmeter? I'd suggest doing a sweep test of the TPS (Throttle Position Sensor) and the closed throttle switch if your car uses one. Look for an open circuit on either device while at idle position. The TPS may have a flat spot there from sitting so much. Other than that, the_boy_toy gave you some pretty good tips too.

    http://www.aa1car.com/library/tps_sensors.htm

    Source(s): ASE Certified Tech
  • Anonymous
    5 years ago

    This Site Might Help You.

    RE:

    A/F Sensor Heater Malfunction Code?

    My pain in the butt 2002 Solara has been having slightly idling problems as of recently, but never threw a code until last night.

    I have a long drive tonight and I was wondering if I now cannot make this drive because of this "A/F Sensor Heater Malfunction." I tried to understand what...

    Source(s): sensor heater malfunction code: https://shortly.im/vimZU
  • 1 decade ago

    Your Mass Air Flow sensor uses a heated wire to gauge how much air is being drawn into the engine. The more air the more cool the wire will get, the sensor relays this information back to the engine managment computer in a voltage or frequency signal.

    EDIT *** A/F can mean air flow or air fuel sensor, since she drives a Solara she must be referring to the maf sensor, no one that works on domestic vehicles uses the term air fuel sensor for an o2 sensor??? They use oxygen or H02s sensor. Oxygen sensors don't measure fuel!!! They only measure oxygen content....that's it. So mabey it is referring to the 02 sensor but it is doing it using contradictive terminology....that's the auto repair biz I guess.

    Source(s): pro tech / shop owner
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