Things to look for with Check engine light

[danigirl]

Hi,

I have posted a few times on several sites and get mixed replies.

I have replaced both O2 sensors (or Air Fuel Sensors), 2 times with OEM sensors. Denso 89467-48011. ( have also replace MAF with OEM and temp switch and PCV--due to other codes.)

The light came back on after 20ish miles both times. Codes read P1133 and P1153.

I asked an expert who has told me there are 2 bank 1 sensors on the back of the firewall. I have 1999 RX 300.

Question 1............How many sensors are on the back of the firewall.

Question 2 ............Any suggestions on why I keep getting the same codes after I replaced the only 2 O2 sensors I can find on the car (and on literature I have found on the web showing where they are located)

Your help is appreciated

[SKperformance]

You only have 3 total for o2 sensors.

1 after the cat

2more , one the left and one on the rear banks.

P1133

Air/Fuel Ratio Sensor Circuit Response Malfunction (Bank 1 Sensor 1)

P1155

Air/Fuel Ratio Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

Have you checked to make sure the pigtail wire is good?

For you to be having multiple codes seem odd since these cars usually never have more than 2 at any given time unless neglected or in an accident.

You replaced the maf,was it new or used?

Did you ever check the rubber intake hose to see if it has any rips or cracks?

[danigirl]

You only have 3 total for o2 sensors.

1 after the cat

2more , one the left and one on the rear banks.

P1133

Air/Fuel Ratio Sensor Circuit Response Malfunction (Bank 1 Sensor 1)

P1155

Air/Fuel Ratio Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

Have you checked to make sure the pigtail wire is good?

For you to be having multiple codes seem odd since these cars usually never have more than 2 at any given time unless neglected or in an accident.

You replaced the maf,was it new or used?

Did you ever check the rubber intake hose to see if it has any rips or cracks?

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3 weeks ago, had oil change. 100 Miles later, check engine light on. Codes for MAF and temp switch. Replaced MAF with new OEM, temp switch (GP Sorensen)

approx 20 miles later, light back on. P1133. Replaced sensor (behind firewall). Did not re-set codes, but light went out by itself after a few miles.

Approx 20 miles later, light back on. P1133 again. Replaced both O2 (bank 1 and bank 2, sensor 1). re-set codes. approx 20 miles later, light back on, now reading P1133 and P1153.

Checked hoses, all appear ok, no leaks. Pigtails good on all O2's that I have installed.

Car fax shows no accidents. I have had car 1 year. Oil change every 3K, changed plugs after purchase. Put approx 14K miles since owned. Car is taken care of and has all preventative maint. It was after the oil change that problem started, but have been told that couldn't have caused any problems.

The only other thing I did to the car the day before light came on was, replaced a bad fuse (15) that controls the power outlet in the back seat.

I work in the after market enviroment and have access to the right parts and people, have everyone stumpled. Have been advised to take back to dealer..not a Lexus dealer, but high end car dealer-know owner well.

I have heard nothing but good things about this car, but losing the love over the past 3 weeks due to this mystery...

Any other recommendations are appreciated. I have been dis-heartened to read the issues around these expensive sensors and MAF everywhere....but felt if I replaced all (due to codes) that problem would be solved. Is there any other "weird" thing I am not getting??

[SKperformance]

Have you ever disconnected the battery to reset the system after any work?

It is tru an oil change will not cause all these problems.

Personally after replacing all these parts i would take it to a dealer for a prognosis. A tech who does the cars all days will figure it out pretty quick.Also an estimate is usually only 30 minutes=$60

[danigirl]

Have you ever disconnected the battery to reset the system after any work?

It is tru an oil change will not cause all these problems.

Personally after replacing all these parts i would take it to a dealer for a prognosis. A tech who does the cars all days will figure it out pretty quick.Also an estimate is usually only 30 minutes=$60

←

We did disconnect battery also, still no luck.

I just dropped off with the dealer I purchased from, so will post again with the results, lets hope for something small and insignificant!!!!(and inexpensive).

I did purchase an extended warranty to last 6 years, 100k (after the regular warranty expired), so hopefully whatever the issue is will be covered.

Thanks for quick replies.

[danigirl]

After 5 days with the mechanic problem finally found:

PCV that I replaced didn't fit (must use OEM)

exhaust manifold is cracked and needs to be replaced. Per Mech-this can cause the codes to go crazy and read different stuff...

booo hooo!!!!$600-700 repair cost. Better than bad ECU...which he was leaning towards.

he did say that the car was in great shape and was well cared for by previous owner, so that makes me feel 100% better as I was falling out of love with this car and quick...I had these same issues with my 4-Runner, but no one could ever diagnose what the check engine light was on for on that one, that was why we parted company and I purchased the RX300.

[SKperformance]

You have just helped cement the issues that show an exhaust leak in a manifold can cause o2 sensor failures when there is none.

[danigirl]

You have just helped cement the issues that show an exhaust leak in a manifold can cause o2 sensor failures when there is none.

←

it gets worse.

Just got off the phone with mechanic. they replaced the manifold and they are still getting the same codes....they have a 2pm appt with Toyota

[bluestu]

I recently replaced the air fuel ratio sensor or O2 sensor as it is sometimes referred to on my RX300 exhaust manifold. The check engine light was on so I had Advance Auto Parts read and print out the code, and I called Lexus to find out which sensor it was. They told me that it was bank 2 sensor 1, the sensor on the manifold. I replaced it with a new one and disconnected the battery terminal to clear the code. The check engine light came on again after about 20mi.. I had Advance Auto read the codes again and it showed the same code. They cleared the codes with the code reader and the guy told me that with the newer cars, sometimes the codes won't clear by just disconnecting the battery. I've driven several hundred miles without the check engine light coming back on so I assume that the problem is fixed.

If anyone is looking to save money on sensor replacement parts, I purchased a Denso mass air flow meter from Advance Auto for $75.oo with core exchange, and I also purchased a Bosch air fuel ratio sensor from a local parts store for less than $200.oo. I put both on myself without much effort.

[RX in NC]

Bluestu made some good points about clearing trouble codes after faulty parts are replaced. Sometimes just disconnecting and immediately reconnecting the battery cables won't do it as he mentioned. In a situation last summer, I had to leave the battery cables disconnected for 45 minutes to an hour to ensure that the trouble code finally cleared and the "check engine" light went off once the sensor was replaced. It did, and it hasn't returned.

[danigirl]

thanks and I will advise the mechanic tomorrow. He did say that both sensors are performing, just very slow, he talked in degrees of performance?????

Toyota swears that my 2nd set of new OEM toyota A/F sensors are both bad. So they replaced one with a sensor off their shelf. Re-set codes. Drove car back to other shop, now only one code, the one that wasn't replaced (for the 3rd time). Mechanic has ordered another direct from Denso, and one direct from Toyota. He will install the Denso direct first and see if that corrects. If it doesn't he will try the Toyota part.

I got my first set of Sensors from AAP, 2nd set direct from Toyota, so will be interesting to see if the 3rd set works.

AAP sells Bosch. Bosch is made my Denso...Toyota purchases their A/F from Denso, all the part numbers are exactly the same and carry the Toyota name????????????

The Bosch part is 13333, bu tthe part itself has the Toyota part number stamped on it.

I do have the factory installed set and last set I put on and will be sending them off to be tested, as this is beyond reasonable; unless of course the 2nd set I put on came off the same MFG line and the guy making the part was smoking crack that day.

Will keep you posted.

As other information, one of the codes I got during this debacle was P0125-.Insufficient Coolant Temperature For Closed Loop Fuel Control. I replaced the temp switch. My mechanic put my original back on and said it works fine. He asked Toyota and they said that definition for that code was incorrect --that the code has to do with A/F sensors.....interesting, wonder how many other codes are misprinted.

Can anyone confirm??

[bluestu]

The code P0125 is caused by a bad fuel air ratio sensor. A bad fuel air sensor causes other codes to pop up.

[bluestu]

Danigirl, I've been reading your posts. Are you sure they are replacing the correct sensors? I doubt if that many sensors would be bad. It is my understanding that bank2 sensor1 & 2 are the two air fuel ratio sensors and bank1 sensor1 is the O2 sensor. The air fuel ratio sensors and the O2 sensor look the same but will not interchange. You should contact Lexus service dept. to find out exactly where these sensors are located. I've come to realize that many techs don't realize that there are three air fuel metering sensors on an RX300. I had to do a good bit of research to try and figure this out myself. This forum has helped me a great deal with troubleshooting such problems. Take your car to a dealership with these kind of problems and they will take all of your money.

[danigirl]

Hi Bluestu.

Where are the 3 A/F sensors located and what are their part numbers?

The only 2 I have been able to ID are Denso part 89467-48011 (this one replaced the 89467-48010-Lexus supersession). bank 1 and bank 2, sensor 1.

There is a O2 sensor located at the cat, which is a different part from the A/F....but I have not gotten any codes for it. bank 1, sensor 2

Please note SK's first response to this thread, is that the 3 sensors you are speaking of? I just want to be sure, cause at this point I am so confused..

http://www.autoshop101.com/forms/h37.pdf, here is a link i found when trying to understand all these codes and sensors. This indicates 2 A/F and 1 02 sensor.

I hate to sound repeatative, but just trying to understand exactly what I am dealing with, so I won't get taken advantage of on invoice day when I pick up this car.

[bluestu]

Is the link you're referring to for an RX300 engine? The diagram doesn't look like the same engine nor does it say that it is for an RX300. I think the code referrals are different each make and model. Whenever I've called Lexus with a code, they always ask me what model and year before than can give me accurate code information. I had my codes read at Toyota one time and they couldn't tell me exactly which sensor the code was referring to because they didn't have the code sheet for an RX300.

[SKperformance]

Blue you may have misunderstood something someone may have wrote somewere else but on a 1mz-fe engine in all RX,ES,camry,avalon engines they all have 3 o2 sensors one on each exhaust manifold (both exactly the same other than a possibility of having different pigtail lenghts) and one after the cat to make sure it is working properly according to the outputs of the first 2 o2 sensors.

An o2 sensor and a air fuel ratio sensor are also the same thing no difference again in the term which is a small filament that has to reach a core temp before it can provide data which is usuable.

Now if you have a consistant o2 problem with a working sensor it leaves only a few things left. A bad wiring connection probably on the pigtail, a malfunctioing maf or wiring (which you mentioned you changed).Basically if the maf read an incorrect amount of air then the ecu will compensate by adjusting the fuel, so if the fuel is ratio'd wrongly by the ecu the end combustion ratio will also be off and set off the code as it cannot see what is actually causing the engine to have a leaner mixture since it is giving it as much fuel as needed for the air it is ingesting.

Make any sense?

I would agree a Lexus dealer is a good bet since right now you are dumping alot of money changing parts without having them thorougly dynamically and bench tested before replacement.

The easiest thign to do is to have a good tech with a proper scan tool to read the exact outputs of the sensors with a Lexus factory manual for exact part specs to see what is actually out of line.

BTW Bosch does not make denso parts denso is japanese and bosch is german,Bosch also makes lots of universal o2 sensors but no OEM toyota parts just bmw,mercedes and so on.

[bluestu]

That's great info and I sort of understand what you're saying. I was told that the sensor after the cat is called an O2 sensor and the ones mounted on the exhaust manifold are called air fuel ratio sensors. The two on the manifold are the same part number but the one after the cat is a different part number and is about half the cost. I've only replaced bank2 sensor1 which read code P1153. It said air fuel ratio sensor on the box when I bought it. That's about all I know.

[SKperformance]

calling an o2 sensor an air fuel ratio sensor is the same as calling a wheel a rim, same difference.

[RX in NC]

All RX300 owners on this forum should be paying careful attention to this particular thread. It is a critical one because most of you will be dealing with these various sensor failures by 60,000 to 70,000 miles. If you choose to let Lexus diagnose and replace your failed sensors, you will pay two to three times more for this service than if you learn where to go for free trouble code diagnosis and then take the time and energy to source the part and do the replacement yourself.

On our particular vehicle, the mass air flow sensor failed at 46,000 miles so it was replaced by Lexus under warranty. The bank 1 air/fuel ratio sensor failed at 69,000 miles and our Lexus service manager agreed to replace it under their goodwill warranty program based upon my complaints concerning the many serious problems we experienced with this vehicle during 2003 and 2004. I still have yet to pay them a penny for service and Lexus has had to absorb over $9,000 in repair costs on this thing as a result.

Danigirl's recent sensor failure experiences are certainly the most unfortunate I've encountered on this forum. But her situation was compounded by her cracked manifold, which is another common problem on the RX300. At the same time our mass air flow sensor had to be replaced, I became aware of the common cracked manifold problem and told the Lexus service manager to check ours carefully when replacing the sensor. She acknowledged that it was cracked so our exhaust manifold was replaced under warranty at 46,000 miles - very low mileage indeed.

Stay on top of these sensor issues. The bottom line is that they are going to fail and the more you know about the situation when it happens, the less likely it will be that you'll have your pocket picked in getting your problem(s) resolved.

By the way Danigirl, I've yet to run across trouble codes on this vehicle that didn't point to the problem that was then solved using the codes, but I'm not surprised that your mechanic was told by Toyota that some of them are misprinted or misleading. Unfortunately there's nothing worse than incorrect documentation from the manufacturer when you're trying to solve a tough maintenance issue, is there? I know your mechanic must be almost as frustrated as you are.

[danigirl]

Blue you may have misunderstood something someone may have wrote somewere else but on a 1mz-fe engine in all RX,ES,camry,avalon engines they all have 3 o2 sensors one on each exhaust manifold (both exactly the same other than a possibility of having different pigtail lenghts) and one after the cat to make sure it is working properly according to the outputs of the first 2 o2 sensors.

An o2 sensor and a air fuel ratio sensor are also the same thing no difference again in the term which is a small filament that has to reach a core temp before it can provide data which is usuable.

Now if you have a consistant o2 problem with a working sensor it leaves only a few things left. A bad wiring connection probably on the pigtail, a malfunctioing maf or wiring (which you mentioned you changed).Basically if the maf read an incorrect amount of air then the ecu will compensate by adjusting the fuel, so if the fuel is ratio'd wrongly by the ecu the end combustion ratio will also be off and set off the code as it cannot see what is actually causing the engine to have a leaner mixture since it is giving it as much fuel as needed for the air it is ingesting.

Make any sense?

I would agree a Lexus dealer is a good bet since right now you are dumping alot of money changing parts without having them thorougly dynamically and  bench tested before replacement.

The easiest thign to do is to have a good tech with a proper scan tool to read the exact outputs of the sensors  with a Lexus factory manual for exact part specs to see what is actually out of line.

BTW Bosch does not make denso parts denso is japanese and bosch is german,Bosch also makes lots of universal o2 sensors but no OEM toyota parts just bmw,mercedes and so on.

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Hi all,

We have spoken with Bosch Corp today. I work for AAP in the Merchansing/Inventory area, so have been fortunate to have our Bosch Product Director assisting me.

SK is correct about Bosch and the sensors they mfg, and since they don't mfg OE Toyota, they purchase their Toyota sensors from Denso directly and re-package in their Bosch packing.

So as you can imagine, Bosch is also anxiosly awaiting the results since these parts are the same parts installed on the Toyota assembly line.

I am still waiting for the mechanic to call back, supposedly had not recv the parts as of 11:30 today.

Will keep you posted and I hope no one ever has to go thru this....

[SKperformance]

Are you sure the bosch parts are exactly the same including the same length of the pigtail and design of the harness plug?

[bluestu]

Danigirl, I'm sorry I gave you some misinformation concerning the sensors. You were correct about where each bank each sensor is located. I crawled up under my car to take a look. bank1 sensor1 is coming off the rear manifold before the cat and bank1 sensor2 is the O2 sensor located after the cat and right before the muffler. bank2 sensor1 is the one on the front manifold and is the one I replaced with the Bosch air fuel ratio sensor.

You are also correct concerning where Bosch gets their parts from. The first Bosch I put on said Toyota Denso on the part and did not work. I took it back and they gave me another that said Bosch and it works fine. I found this out when I called the parts store today. They told me the one I returned said Denso on it. The salesman also told me that sometimes Bosch gets their parts from other manufactuers when they run out of a certain part. Maybe the parts Bosch received from Denso were not the correct ones??? If they can't solve your problem with the sensors, I would check around each manifold for leaks or cracks. Lexus service dept. told me that can sometimes cause a sensor to screw up. Good Luck!!!

[danigirl]

$591.00 in diagnostic time & intallation of manifold and sensors(which is still less than he actually did)

$205.61 for manifold

$25.25 for gasket

$8.03-gasket

$7.16-PCV valve

$227.52-1 Toyota dealer shelf sensor - 89467-48011

$227.52-mechanic ordered Denso sensor - 234-9009

Paying out all this money for a 6 year old luxury car with 61,900 miles on it, when the piece of crap Mazda I had forever never needed anything but gas, an oil change and a good cleaning every once in a while & got 35 MPG.............PRICELESS

Anyhoo....It appears that my extended warranty does cover sensors, so I am suppose to get approx $444.04 back from the warranty company.

Further, I will be filing a warranty defect claim with Bosch as the parts they claim fix my car...DONT, but they do have the exact same part number and Toyota logo, so this should be interesting.

I will update tomorrow after I talk with them...

[bluestu]

What about your check engine light??? Have you driven it far enough to see if your problem is fixed??? Something's up with those Bosch sensors that say Toyota Denso. The fact that I had a bad one and you had two indicates that they are probably not the correct ones for the RX. The one I replaced it with that says Bosch works fine and has a heat resistant mesh casing for the wires.

[danigirl]

I have traveled 25 miles , no light....so that is a relief.

Yes, something funny in Boschland, but I am on it and will update as soon as I know something.

I will be returning the sensors to our Product Director to have analyzed and address the excessive costs I have incurred using the Bosch parts that they advertise are the correct replacment sensor. Bosch is waiting for us to advise the results of this situation.

Also, the mechanic said the sensors worked, they just didn't perform accurately in the Lexus. "Slow response". He said that physically in appearance, they are not the same (and they weren't). The Toyota logo on the Bosch part also didn't look the same as they Toyota logo on my factory installed sensor, however, the part number was the correct Toyota superceeded part number.

Stay tuned!!