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Need Help O2 Sensors?


vmaren
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Just got back from lexus with a estimate for $800. Just purchased a 99 ES 300 with 32k and after two weeks the CEL and THe TRack off light went on. The car also feels like it is misfiring. Went to Lexus for Diagnostic and 97 dollars later it is $800 to fix. The error codes that came up are as follows P0171,P0300,P0301,P0303,P0305. They told me that Bank 1 Sensor 1 was slow and that Bank 2 Sensor 2 was not working? What I don't know is what I should do next. The Sensor after the CAT is $144 and the one on the manifold is $112 both OE. Question #1 Why did the error codes for the Senors come up? Question #2 If the sensor is acting slow does that mean that it needs to be replaced or is it acting slow based on Bank2 sensor 1 not working? Question # 3 Can anyone with expertise in this topic give me direction on how to handle this problem?

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Just got back from lexus with a estimate for $800. Just purchased a 99 ES 300 with 32k and after two weeks the CEL and THe TRack off light went on. The car also feels like it is misfiring. Went to Lexus for Diagnostic and 97 dollars later it is $800 to fix. The error codes that came up are as follows P0171,P0300,P0301,P0303,P0305. They told me that Bank 1 Sensor 1 was slow and that Bank 2 Sensor 2 was not working? What I don't know is what I should do next. The Sensor after the CAT is $144 and the one on the manifold is $112 both OE. Question #1 Why did the error codes for the Senors come up? Question #2 If the sensor is acting slow does that mean that it needs to be replaced or is it acting slow based on Bank2 sensor 1 not working? Question # 3 Can anyone with expertise in this topic give me direction on how to handle this problem?

STOP! O2 sensors may be sluggish but the o2 performance codes are not displayed so do not replace them. P0171 is a fuel trim error. The MOST LIKELY cause at this mileage is dust particles on the Mass Air Flow sensor wire. Find the air cleaner, look at the big black hose that goes to the engine coming out of the air filter box. In this hose there lives a MAF. Remove 2 mounting bolts and 5 wire conector. Purchase a can of aeresol brake cleaner. invert the sensor and look down the little bazooka tube thingy...see those wires inside it? spray them with a good long blast of brake clean...now do it again. Reinstall sensor. Remove efi fuse for 20 seconds to clear codes.

Now then...P0300 is a random missfire code, p301 is #1 cylinder specific missfire, P303 is #3 etc. I smell a rat. Is your engine clean looking like they just presure washed it? bet it does. The front 3 plugs have coils on them with sparkplug wires going to the back 3 cylinders. Very odd for 3 missfires on the same bank unless someone misstimes the tbelt. 32k the tbelt should be oem. So I think when thier detail department presure washed the engine, they got water past the plugwires in the back head and you now have intermitant missfires. The wires need to come out of the head, dried off and remove and inspect the plugs for carbon tracking. $900 for o2 sensors won't cure squat. Just my 2cents worth and diagnosis over the net is worth what you pay for it. Try a local toyota dealer and ask for thier MDT to clean and dry your plugs and wires for $80 if you can't do it yourself. We did have a bad run of coils but 3 dead ones all at 32K all aon the same bank....No. Please post your results.

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my bank 1 sensor 1 is broke, but i mistakely replaced the bank 2 sensor 1. but i wanna put the good one back to bank 2 sensor 1. now the question is the sensor i putted on bank 2 sensor 1 can also fit in bank 1 sensor 1?

Electrically they are the same, it is the harness lenth that is different. May work fine.

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agreed they are the same

what octane gas are you using in your cars that need the o2 sensors replaced?

Okay, Thanks for your response. I will start with cleaning the MAF and then dry out the wires. You hit the nail right on the head about cleaning the motor, but it was I who did. I took it over to my local self wash and pressure cleaned the engine after I bought it. It ran fine for about two weeks or 1/2 tank of gas before the CEL and Track off light had illuminated? I also at the same time started with 87 octane and had only burned half of the tank since then. We have had a lot of snow in my area, so I have been using my other car. The Manual states that 87 octane is okay, but premium is perferred. Question#1 Does anyone think that octane can be playing a factor in my situation? Thanks Vince

I will also post all my results.......

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agreed they are the same

what octane gas are you using in your cars that need the o2 sensors replaced?

Okay, Thanks for your response. I will start with cleaning the MAF and then dry out the wires. You hit the nail right on the head about cleaning the motor, but it was I who did. I took it over to my local self wash and pressure cleaned the engine after I bought it. It ran fine for about two weeks or 1/2 tank of gas before the CEL and Track off light had illuminated? I also at the same time started with 87 octane and had only burned half of the tank since then. We have had a lot of snow in my area, so I have been using my other car. The Manual states that 87 octane is okay, but premium is perferred. Question#1 Does anyone think that octane can be playing a factor in my situation? Thanks Vince

I will also post all my results.......

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agreed they are the same

what octane gas are you using in your cars that need the o2 sensors replaced?

Okay, Thanks for your response. I will start with cleaning the MAF and then dry out the wires. You hit the nail right on the head about cleaning the motor, but it was I who did. I took it over to my local self wash and pressure cleaned the engine after I bought it. It ran fine for about two weeks or 1/2 tank of gas before the CEL and Track off light had illuminated? I also at the same time started with 87 octane and had only burned half of the tank since then. We have had a lot of snow in my area, so I have been using my other car. The Manual states that 87 octane is okay, but premium is perferred. Question#1 Does anyone think that octane can be playing a factor in my situation? Thanks Vince

I will also post all my results.......

Vince, you just saved $900. Congradulations. Octane will not affect the MAF or fuel trim. May cause ping depending on driving habits. Sounds like next time I'm in RI you owe me a Rum & coke.

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You hit the nail right on the head about cleaning the motor, but it was I who did. I took it over to my local self wash and pressure cleaned the engine after I bought it.

:chairshot: :chairshot: don't do that again!!!

just kidding. If you want to clean the engine, have is steam cleaned, never use high pressure.

you might want to place a call to the service manager where you had the diagnostic done. (was it Inskip Lexus or Lexus of Norwood?) A little feedback is always appreciated since they missed the obvious that was pointed out by an extremely knowledgable Lexus Tech. (you owe him several rum&cokes for the money saved.) :cheers:

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you might want to place a call to the service manager where you had the diagnostic done. (was it Inskip Lexus or Lexus of Norwood?) A little feedback is always appreciated since they missed the obvious that was pointed out by an extremely knowledgable Lexus Tech. (you owe him several rum&cokes for the money saved.) :cheers:

Thanks Steve, but since I've never been to RI he's probably safe I'll never collect.

The funny thing about autoshops, inde or dealer, is that for every 8-10 guys there are usually 2 or 3 aces, 2 or 3 good ones and 3 or 4 young bucks who try hard. Chances are where ever he took it the Aces and journeymen were just busy with tough cars and the simple SES light went to a newB. Fuel trim readings take experience at looking at the scanner because there are no specs. I explained in the IS forum not long ago how MAF's work and why they can cause a hesitation(and got crushed for a 2 page post). When they get dirty, they think less air is going into an engine than realy is. The ECU fires injectors acordingly. But since more air is ACTUALLY going into the engine this is not enough fuel (so say the O2 sensors). The ECU says ok, we are lean for this air flow reading, so I will add more fuel , and more and...soon it takes 20% more fuel than it should (acording to the MAF) and 20% is the threshold for setting P0171 lean code. They should be cleaned at every tuneup.

Vince said..."It ran fine for about two weeks or 1/2 tank of gas before the CEL and Track off light had illuminated?"

Welcome to 2 trip detection logic. If you get a cylinder missfire that misses over 50% of the time it sets in one trip with a "flashing CEL", below 50% it takes 2 trips and since it may not always check for missfire it may take more than 2 key cycles to set the code. Start-drive-shutdown does not always equal a drive cycle. Water will seep into the plug bores when you washed it and then beome a vapor due to eng heat and not missfire on the way home. It needs to fully cool and condense in the bore at least one cycle before it dribbles down close enough to the plug base to provide a gound path. In theory it would take at least 4 long drives after washing to get the light. Glad it was a simple fix for you...you will enjoy your Lex for years to come.

Now I think I'll get started on the Meyers without you.....Regards, Mike

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you might want to place a call to the service manager where you had the diagnostic done. (was it Inskip Lexus or Lexus of Norwood?) A little feedback is always appreciated since they missed the obvious that was pointed out by an extremely knowledgable Lexus Tech. (you owe him several rum&cokes for the money saved.) :cheers:

Thanks Steve, but since I've never been to RI he's probably safe I'll never collect.

The funny thing about autoshops, inde or dealer, is that for every 8-10 guys there are usually 2 or 3 aces, 2 or 3 good ones and 3 or 4 young bucks who try hard. Chances are where ever he took it the Aces and journeymen were just busy with tough cars and the simple SES light went to a newB. Fuel trim readings take experience at looking at the scanner because there are no specs. I explained in the IS forum not long ago how MAF's work and why they can cause a hesitation(and got crushed for a 2 page post). When they get dirty, they think less air is going into an engine than realy is. The ECU fires injectors acordingly. But since more air is ACTUALLY going into the engine this is not enough fuel (so say the O2 sensors). The ECU says ok, we are lean for this air flow reading, so I will add more fuel , and more and...soon it takes 20% more fuel than it should (acording to the MAF) and 20% is the threshold for setting P0171 lean code. They should be cleaned at every tuneup.

Vince said..."It ran fine for about two weeks or 1/2 tank of gas before the CEL and Track off light had illuminated?"

Welcome to 2 trip detection logic. If you get a cylinder missfire that misses over 50% of the time it sets in one trip with a "flashing CEL", below 50% it takes 2 trips and since it may not always check for missfire it may take more than 2 key cycles to set the code. Start-drive-shutdown does not always equal a drive cycle. Water will seep into the plug bores when you washed it and then beome a vapor due to eng heat and not missfire on the way home. It needs to fully cool and condense in the bore at least one cycle before it dribbles down close enough to the plug base to provide a gound path. In theory it would take at least 4 long drives after washing to get the light. Glad it was a simple fix for you...you will enjoy your Lex for years to come.

Now I think I'll get started on the Meyers without you.....Regards, Mike

I just want to thank you all for your help and if it cost just a drink, so be it. Sure beats $800 Inskip Lexus rip off. First off I checked all the plugs and every one was bone dry with no water or condensation. Second, I cleaned the MAF with brake cleaner and reset the CEL and Track off light by taking out the EFI fuse for a minute or two. Bamm it is running like a charm. I only drove it for about 20 miles or so, but it runs flawless, with no misfire detected at all. Runs nice and smooth. If this was the cure, then how the hell can Inskip want to charge $800???

I think that it was the MAF in the end. I hope that this post can possible help some others on the forum. I will report back if there are any problems in the future. Once again Thanks to all............... Vince

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If this was the cure, then how the hell can Inskip want to charge $800???

I think that it was the MAF in the end. I hope that this post can possible help some others on the forum. I will report back if there are any problems in the future. Once again Thanks to all...............          Vince

Vince, in the shop manual for the 1MZFE (at least in my 2002 but its probably the same of rthe 1999) the trouble areas are listed in an order for each code.

Under code P0171 it lists in this order:

Air intake (hose loose)

Fuel line pressure

Injector blackage

open or short in A/F sensor circuit

A/F sensor malfunction

Intake flow meter

Rather than test the two items before the AF sensors and then test the AF sensor and then test the MAF sensor as the inspection procedure illustrates, it sounds like the dealer wanted to just "test by replacement" and hope it goes away. I'm guessing on this next one but I think the MAF sensor replacement is overall less expensive so they go with the mose profitable.?.

steviej

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If this was the cure, then how the hell can Inskip want to charge $800???

I think that it was the MAF in the end. I hope that this post can possible help some others on the forum. I will report back if there are any problems in the future. Once again Thanks to all...............          Vince

Vince, in the shop manual for the 1MZFE (at least in my 2002 but its probably the same of rthe 1999) the trouble areas are listed in an order for each code.

Under code P0171 it lists in this order:

Air intake (hose loose)

Fuel line pressure

Injector blackage

open or short in A/F sensor circuit

A/F sensor malfunction

Intake flow meter

Rather than test the two items before the AF sensors and then test the AF sensor and then test the MAF sensor as the inspection procedure illustrates, it sounds like the dealer wanted to just "test by replacement" and hope it goes away. I'm guessing on this next one but I think the MAF sensor replacement is overall less expensive so they go with the mose profitable.?.

steviej

Sorry, I have spoke to soon. The problem has come back. Both the CEL and the Track off light have illuminated and the engine has begun to run a little rough. I have also noticed that the catalyic converter is getting real hot, reason being that it is pinging when I shut down the car. I have the print outs from the diaganostic machine from lexus, but cannot make out what it really means? It has percentages next to each cylinder 1-6 with the error codes. But Inskip Lexus insisted that it was the O2 sensor? Question#1 Can all the experts here on the forum reevaluate this problem? Thanks Much Vince

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If this was the cure, then how the hell can Inskip want to charge $800???

I think that it was the MAF in the end. I hope that this post can possible help some others on the forum. I will report back if there are any problems in the future. Once again Thanks to all...............          Vince

Vince, in the shop manual for the 1MZFE (at least in my 2002 but its probably the same of rthe 1999) the trouble areas are listed in an order for each code.

Under code P0171 it lists in this order:

Air intake (hose loose)

Fuel line pressure

Injector blackage

open or short in A/F sensor circuit

A/F sensor malfunction

Intake flow meter

Rather than test the two items before the AF sensors and then test the AF sensor and then test the MAF sensor as the inspection procedure illustrates, it sounds like the dealer wanted to just "test by replacement" and hope it goes away. I'm guessing on this next one but I think the MAF sensor replacement is overall less expensive so they go with the mose profitable.?.

steviej

Sorry, I have spoke to soon. The problem has come back. Both the CEL and the Track off light have illuminated and the engine has begun to run a little rough. I have also noticed that the catalyic converter is getting real hot, reason being that it is pinging when I shut down the car. I have the print outs from the diaganostic machine from lexus, but cannot make out what it really means? It has percentages next to each cylinder 1-6 with the error codes. But Inskip Lexus insisted that it was the O2 sensor? Question#1 Can all the experts here on the forum reevaluate this problem? Thanks Much Vince

Vince, Missfire is caused by compression loss, coils, wires, plugs, cam timing... 20 years, never seen an O2 sensor cause missfire. What are the % next to each cyl? I think you need to pull all 6 plugs and wires and check plugs for hairline carbontracks....looks like pencil lead down the porcilin. Spray some of your leftover brake clean down each plug bore to remove any moisture traces. Ohm check plugwires when they are out...8-15Kohms is nominal. Does your printout give a reading next to cal load? what about MAF g/sec? injector M/sec? post these if it is on there along with short term fuel trim. We can get this. I think you fixed 1 problem but are still looking at missfire caused by water intrusion that has carbon tracked a plug or two. Look/listen for vac leaks hoses off at right side of the plenum.

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I tired to make excuses for the other dealer missing the MAF issue and fuel trim P0171, if they are sticking by O2 sensors to fix a miss, then I would rather you pay $10 to call me for 1/2 hour long distance at work or home than take it back there. You can remove ALL O2 sensors from a car lay them on the bench and start the car...you will get an exhaust leak, O2 sensor performance code, O2 sensor heater ckt code BUT NO MISSFIRE.

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Make sure your PCV hose is still conected to the intake, not just the valve, at the right side of the plenum.. Last time you pulled rear plugs you are right next to it and might have bumped it. It's real easy to bump. This will give a return of P0171 ('cuz now it is lean) and you will have missfire % on all 6 cyls...before we only had miss on 1, 3, 5.

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Make sure your PCV hose is still conected to the intake, not just the valve, at the right side of the plenum.. Last time you pulled rear plugs you are right next to it and might have bumped it.  It's real easy to bump.  This will give a return of P0171 ('cuz now it is lean) and you will have missfire % on all 6 cyls...before we only had miss on 1, 3, 5.

I can not post the picture of the printouts from Lexus here on the forum. If someone can email me at vmaren@aol.com. I will e-mail you the printouts. I guess that you would not post your e-mail? I promise I will only e-mail you the printouts. Thanks ........Vince

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click on my member name and my email is avaliable....MKBeyer*nospam-*@aol.com

remove the *nospam-*

I am editing you post ifixem

to add the words *nospam*

Other wise searchengines can find your email and add you to a list of garbage quite easily.

For everyone else please take note.

I don;t favour openly adding an email adress but if you do make an easy alteration to make it alittle harder to help spam find you.

Edited by SKperformance
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vmaren, go to AutoZone and get the codes reread. We are assuming that the codes you have now are the same codes that you had before you cleaned the MAF sensor. On a long shot, they may be different now after your work.

They may be the same, but it is just a hunch.

steviej

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p0125 insuf coolant temp for closed loop map

meaning it is running rich at an o2 sensor from lack of heat

p0136 bank2 sensor 1 malfunction

another o2 sensor issue

p0171 error of running rich on the o2

either the pigtail

o2 itself

a coil is not igniting

or an injector is stuck open

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Thanks Mike and Steve for all your help. The problem is finally fixed. I rechecked the plug tubes for any signs of water/condensation which turned out to be negative. I cleaned the MAF again with brake cleaner and replaced both the O2 sensor behind the catalytic converter as well as the A/F sensor at the bank against the firewall, then reset the EFI by pulling the fuse and after about 10 on off cycles no Trac off/CEL light and the car is running great. I also did as Mike had suggested and checked the PCV and it was nice and snug. One thing I can say is that after changing both sensors I did not reset the EFI and the car was running like crap and both the Trac off light and the CEL lights were illuminated, but after I reset the EFI it ran great. Anthor thing I noticed is that every time I flawed it on the road a bunch of smoke was blowing out the exhaust. I guess a lot of carbon was building up in the cats and exhaust, and after about 30 minutes the exhaust was burning clean with no signs of smoke or discharge. My total cost was about 3 hours labor and $127 for the cat back sensor (OE) and $227 for the A/F sensor (OE). I guess that if the car has California emmisions which mine has, then the Exhaust manifold sensors are called air/fuel and if it is not then it would just be a o2 sensor. They look exactly alike so take note. Another helpful hint is that in order to replace the cat back O2 sensor you need to remove the drivers side seat and pull back the carpet to get at the plug it is about halfway between the center console and the drivers side door located on the floor, or you may go half assed and buy a generic O2 sensor and splice the wires? Also when I checked the plugs at Cylinder#1&5 they were black and full of carbon, I guess you can call that a rich fuel mixture. I also checked all the intake hoses before the trottle body for any leaks and a firm connection. I hope somebody may benifit from this post. Once again thanks to Mike and Steve. Vince

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