Dyllen

RX300 - VSC and Engine Check Lights On at the same time, try to reset but cannot, remove the EFI fuse, but still the same. Checked and found out Code P1155 Air/Fuel Ratio Sensor Heater Circuit Malfunction the mechanics said its the air flow sensor defective, is it true? try to check and install new flow sensor, but the VSC lights still on also the check engine lights. suggest by the mechanics, its the O2 sensor, 2 nos. have to be replaced. anyone can help to solve my problem, is it true to replace the O2 sensor.

thks

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its not the O2 sensor, its the air fuel sensor. ive replaced them, 2 nos and now its ok, in normal working condition.

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what was the part numbers and OEM of the Air Fuel sensors you replaced?

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DENSO Part # 2349009

Oxygen Sensor: Air Fuel Ratio Sensor #8946748011

Its better you to check from http://www.rockauto.com

My one is model 2001. U said u replace the both A/F sensor, are they the same part number from the existing u replaced? is it really new? It Should be the same part number, i've try different part number on the air/fuel sensor but it not works. Hope thats help u. thks

code read P1133-I replaced O2 sensor behind firewall.  light on again, replaced MAF with OEM part, light on again, giving same P1133 code...NOW what? 

Anyone have the same issue or can you help

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P1133 - Air/Fuel Ratio Sensor Circuit Response Malfunction. It might be the Air/Fuel Sensor located. One air/fuel sensor located at the exhaust manifold and one before the catalytic converter, both the same part and same function. Normally both sensor to be replace. The rear sensor (after the catalytic converter) is the O2 sensor. Its look like your air/fuel sensor malfunction.

FYI..... I got P1155 - Air/Fuel Ratio Sensor Heater Circuit Malfunction, its look like the same parts mentioned (air/fuel sensor). Replaced, and the engine check lights no more.

Hope that helps.

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thanks

What is the difference in an Air/Fuel Ratio Sensor and an O2 sensor??

I replaced the front one first, light came back on. Talked to a Lexus 'expert" who said I replaced wrong one. Put O2 on the the back of the firewall and light still on, that is when I got the MAF code, replaced it with OEM part, and light on again, giving same code it gave originally. So am going to replace both O2 Sensors and see what happens. What is irritating is that it is only coding one trouble spot..not 2.

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The two Air/Fuel Sensor and O2 sensor both work differently. Yes, normally have to change both of the sensor. Hopefully can solve ur problem.

Might helps u, go to.... http://www.boschusa.com/AutoParts/FAQs/OxygenSensors/

Q. What does an oxygen sensor do?

A. The oxygen sensor sends a signal to the engine computer based on the amount of oxygen in the exhaust gas. This signal is used by the engine ECU to fine-tune the mixture to the optimum level for maximum catalyst efficiency and longevity. A worn-out oxygen sensor can cause excessive gasoline consumption, elevated exhaust emissions, accelerated catalytic converter damage failures and cause engine performance problems such as surging and hesitating.

Q. Except for the connector assembly, aren't all oxygen sensors basically the same?

A. NO. There are five fundamentally different types of oxygen sensors: unheated thimble, heated thimble, planar, wide-band and titania. Within each sensor type, sensors vary in the design of the ceramic element, heater element and protection tube design, all of which affect sensor operation.

Q. Where are oxygen sensors located and do they have different purposes?

A. Oxygen sensors have been standard equipment on almost all passenger cars and light trucks with gasoline engines since 1980-1981. Most vehicles built before the mid-90’s have one or two oxygen sensors (two were used on selected V6 and V8 engines starting in the late 1980s). Oxygen sensors are normally located in the exhaust system before the catalytic converter to measure exhaust emissions as they come from the engine combustion chambers. In 1996 with the federal mandated use of on-board-diagnostic systems (OBDII), vehicles also require additional oxygen sensors after the catalytic converter, to ensure that the converter is operating properly.

code read P1133-I replaced O2 sensor behind firewall.  light on again, replaced MAF with OEM part, light on again, giving same P1133 code...NOW what? 

Anyone have the same issue or can you help

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P1133 - Air/Fuel Ratio Sensor Circuit Response Malfunction. It might be the Air/Fuel Sensor located. One air/fuel sensor located at the exhaust manifold and one before the catalytic converter, both the same part and same function. Normally both sensor to be replace. The rear sensor (after the catalytic converter) is the O2 sensor. Its look like your air/fuel sensor malfunction.

FYI..... I got P1155 - Air/Fuel Ratio Sensor Heater Circuit Malfunction, its look like the same parts mentioned (air/fuel sensor). Replaced, and the engine check lights no more.

Hope that helps.

As skperformance suggested a couple of days ago, my wife had AutoZone read the trouble codes again yesterday afternoon after I cleared the codes in the morning by disconnecting the battery terminals for about 15 minutes.  One of the original codes from last week has disappeared, but the two remaining codes appear to indicate an oxygen sensor problem.  The question now is  -  which one?  This vehicle apparently has four oxygen sensors, and unfortunately they are not all identical part numbers.  I've called a couple of local independent service shops who specialize in Lexus and Toyota, and they haven't offered a solution that will allow me to nail down which oxygen sensor is creating the problem.  Our Lexus dealership just wants us to bring the vehicle in and drain our checkbook.

So what's next, guys?  I sure don't want to start guessing and wind up having to purchase all four oxygen sensors at about $200 a pop before I solve our problem. The remaining trouble codes are P01130 and P01135.

I've heard that some of these oxygen sensors are located before the catalytic converter while others are located after it.  Can anyone offer a clear explanation where all four of these sensors can be found, what they are individually called, and how you can get to them?

I'm also wondering whether specific preventive maintenance actions can help preserve the longevity of these seemingly fickle oxygen sensors.  With the typical RX300, they seem to start failing between 60,000 and 80,000 miles (we're just over 69,000 miles right now).  Do the various fuel injector cleaner additives or other component cleaners on the market add to the lifespan of oxygen sensors?   

As always, thanks for the assistance from those of you who have been through these battles before and paved the way for the rest of us....

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RX in NC,

   There are three O2 sensors on the '99.  I'd assume it's the same for the '00 since very few changes were between those model years.  The '99 has one sensor just below each exhaust manifold and a third one just prior to the catalytic converter.  I am quite sure the front two are the exact same part.  The rear one is different however.  The front is the easiest to see as it's right under the hood downward of the exhaust manifold.  It is angled slightly toward the drivers side of the vehicle.

   Hope that helps.

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how many O2 sensor are they on RX300. what i know only two (2) sensor. but when the mechanic checked. i got three (3) sensor and again different cable connector from the others two (2) sensor models.

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there are 2 (same part) in the front before the catalyst and one behind (different part from the other 2) The 2 front ones are $189, the one on the back 100. #1Motormart.com So, a total of 3 sensors.

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thks for ur reply, u r right, the front two sensor actually air fuel sensor and the last sensor (below) O2 sensor. I've change both air/fuel sensor (before the catalyst). and no more engine check lights. thks

RX300 - VSC and Engine Check Lights On at the same time, try to reset but cannot, remove the EFI fuse, but still the same. Checked and found out Code P1155 Air/Fuel Ratio Sensor Heater Circuit Malfunction the mechanics said its the air flow sensor defective, is it true? try to check and install new flow sensor, but the VSC lights still on also the check engine lights. suggest by the mechanics, its the O2 sensor, 2 nos. have to be replaced. anyone can help to solve my problem, is it true to replace the O2 sensor.

thks

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its not the O2 sensor, its the air fuel sensor. ive replaced them, 2 nos and now its ok, in normal working condition.

how many O2 sensor are they on RX300. what i know only two (2) sensor. but when the mechanic checked. i got three (3) sensor and again different cable connector from the others two (2) sensor models.

RX300 - VSC and Engine Check Lights On at the same time, try to reset but cannot, remove the EFI fuse, but still the same. Checked and found out Code P1155 Air/Fuel Ratio Sensor Heater Circuit Malfunction the mechanics said its the air flow sensor defective, is it true? try to check and install new flow sensor, but the VSC lights still on also the check engine lights. suggest by the mechanics, its the O2 sensor, 2 nos. have to be replaced. anyone can help to solve my problem, is it true to replace the O2 sensor.

thks

RX300 - Code P1155 Air/Fuel Ratio Sensor Heater Circuit Malfunction. the mechanics said its the air flow sensor, is it true? try to check and install new flow sensor, but the VSC lights still on also the check engine lights. suggest by the mechanics, its the O2 sensor, 2 nos. to be replaced. anyone can help to solve my problem, is it true to replace the O2 sensor.

thks

My RX300 got VSC and its engine check lights on.... try to open gas cap and closed, but still lights going on. Checked, and Air Flow Sensor mulfunctioning, and try to confirmed by replacing with new A/F Sensor, but the lights still on. Can anyone help me to solve this problem. lastly are the ABS connected to this problem?

thks

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Is the black rubber hose behind the air filter box disconnected from the metal tube that it attaches to? This is a common problem and happens when someone checks the air filter. Pull the EFI fuse to reset the light.

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The rubber hose is connected. Will try to pull the EFI fuse to reset the light.

thks

Try already to pull out the EFI fuse and put it back, the lights off for a few seconds only and lights come back again. Pls, if there's any other way to solve this problem.

thks

My RX300 got VSC and its engine check lights on.... try to open gas cap and closed, but still lights going on. Checked, and Air Flow Sensor mulfunctioning, and try to confirmed by replacing with new A/F Sensor, but the lights still on. Can anyone help me to solve this problem. lastly are the ABS connected to this problem?

thks