IS 500 - CEL problem and update
#46
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O2 sensors measure oxygen, nothing else, hence the name...more oxygen in the exhaust and the car is running Lean, less oxygen, it's running Rich.
If you have an exhaust leak near an O2 sensor, this may introduce more oxygen for the sensor to detect.
Far be it from me to call into question the brilliant minds that author the repair manual, but the code says "Slow Response - Rich to Lean"...if you introduced more oxygen into the exhaust, it should be the opposite "Slow Response - Lean to Rich".
And notice in the code description is states this occurs after fuel cut...during fuel cut the oxygen volume in the exhaust is even greater, so if you add an exhaust leak to that, the O2 sensor should be reading Lean like crazy.
For those that had the dealer replace the exhaust gasket and it didn't fix the issue...no kidding, I couldn't see why it would.
The vehicles that had the issue, based on the code description you should have been decelerating when the CEL came on.
Fuel cut most commonly occurs during deceleration. When accelerating and cruising with constant throttle you shouldn't be going into fuel cut.
I don't know, just my two cents. Maybe I'm completely out to lunch here.
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wthrman2 (01-26-22)
#47
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In looking at the code and possible causes (the 3 bullets), I'm struggling to think why an exhaust leak is even a possibility as a cause.
O2 sensors measure oxygen, nothing else, hence the name...more oxygen in the exhaust and the car is running Lean, less oxygen, it's running Rich.
If you have an exhaust leak near an O2 sensor, this may introduce more oxygen for the sensor to detect.
Far be it from me to call into question the brilliant minds that author the repair manual, but the code says "Slow Response - Rich to Lean"...if you introduced more oxygen into the exhaust, it should be the opposite "Slow Response - Lean to Rich".
And notice in the code description is states this occurs after fuel cut...during fuel cut the oxygen volume in the exhaust is even greater, so if you add an exhaust leak to that, the O2 sensor should be reading Lean like crazy.
For those that had the dealer replace the exhaust gasket and it didn't fix the issue...no kidding, I couldn't see why it would.
The vehicles that had the issue, based on the code description you should have been decelerating when the CEL came on.
Fuel cut most commonly occurs during deceleration. When accelerating and cruising with constant throttle you shouldn't be going into fuel cut.
I don't know, just my two cents. Maybe I'm completely out to lunch here.
O2 sensors measure oxygen, nothing else, hence the name...more oxygen in the exhaust and the car is running Lean, less oxygen, it's running Rich.
If you have an exhaust leak near an O2 sensor, this may introduce more oxygen for the sensor to detect.
Far be it from me to call into question the brilliant minds that author the repair manual, but the code says "Slow Response - Rich to Lean"...if you introduced more oxygen into the exhaust, it should be the opposite "Slow Response - Lean to Rich".
And notice in the code description is states this occurs after fuel cut...during fuel cut the oxygen volume in the exhaust is even greater, so if you add an exhaust leak to that, the O2 sensor should be reading Lean like crazy.
For those that had the dealer replace the exhaust gasket and it didn't fix the issue...no kidding, I couldn't see why it would.
The vehicles that had the issue, based on the code description you should have been decelerating when the CEL came on.
Fuel cut most commonly occurs during deceleration. When accelerating and cruising with constant throttle you shouldn't be going into fuel cut.
I don't know, just my two cents. Maybe I'm completely out to lunch here.
#48
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In looking at the code and possible causes (the 3 bullets), I'm struggling to think why an exhaust leak is even a possibility as a cause.
O2 sensors measure oxygen, nothing else, hence the name...more oxygen in the exhaust and the car is running Lean, less oxygen, it's running Rich.
If you have an exhaust leak near an O2 sensor, this may introduce more oxygen for the sensor to detect.
Far be it from me to call into question the brilliant minds that author the repair manual, but the code says "Slow Response - Rich to Lean"...if you introduced more oxygen into the exhaust, it should be the opposite "Slow Response - Lean to Rich".
And notice in the code description is states this occurs after fuel cut...during fuel cut the oxygen volume in the exhaust is even greater, so if you add an exhaust leak to that, the O2 sensor should be reading Lean like crazy.
For those that had the dealer replace the exhaust gasket and it didn't fix the issue...no kidding, I couldn't see why it would.
The vehicles that had the issue, based on the code description you should have been decelerating when the CEL came on.
Fuel cut most commonly occurs during deceleration. When accelerating and cruising with constant throttle you shouldn't be going into fuel cut.
I don't know, just my two cents. Maybe I'm completely out to lunch here.
O2 sensors measure oxygen, nothing else, hence the name...more oxygen in the exhaust and the car is running Lean, less oxygen, it's running Rich.
If you have an exhaust leak near an O2 sensor, this may introduce more oxygen for the sensor to detect.
Far be it from me to call into question the brilliant minds that author the repair manual, but the code says "Slow Response - Rich to Lean"...if you introduced more oxygen into the exhaust, it should be the opposite "Slow Response - Lean to Rich".
And notice in the code description is states this occurs after fuel cut...during fuel cut the oxygen volume in the exhaust is even greater, so if you add an exhaust leak to that, the O2 sensor should be reading Lean like crazy.
For those that had the dealer replace the exhaust gasket and it didn't fix the issue...no kidding, I couldn't see why it would.
The vehicles that had the issue, based on the code description you should have been decelerating when the CEL came on.
Fuel cut most commonly occurs during deceleration. When accelerating and cruising with constant throttle you shouldn't be going into fuel cut.
I don't know, just my two cents. Maybe I'm completely out to lunch here.
#49
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Rich to Lean is the expected behavior, but the Slow Response is the problem...it's taking too long to do the expected behavior.
If you introduce more oxygen into the exhaust system then this would increase the time the sensor would take to move from a Lean to Rich reading...hence the alternate wording I suggested.
If you throw more oxygen at the sensor constantly it's never going to read Rich...but the ECU will also try to throw more fuel at the engine in an attempt to move the sensor reading. Eventually the ECU give up and throw a code that something is wrong.
#50
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Yes unfortunately they (Lexus USA) are on a guided track… See my post# 18 & 31 in this thread..
The gaskets and flange alignment are the first inexpensive attempts… If there are bad O2 issues, that’s where it will become more costly for the warranty fixes..
Last but not least it can also be a software issue if the physical parts do not resolve the issue permanently..
Hoping they get to the bottom of this soon..![Dunno](https://www.clublexus.com/forums/images/smilies/13879dunno.gif)
Joe Z
The gaskets and flange alignment are the first inexpensive attempts… If there are bad O2 issues, that’s where it will become more costly for the warranty fixes..
Last but not least it can also be a software issue if the physical parts do not resolve the issue permanently..
Hoping they get to the bottom of this soon..
![Dunno](https://www.clublexus.com/forums/images/smilies/13879dunno.gif)
Joe Z
#51
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Given the way this O2 Sensor code issue is trending i think the dealer tech that mentioned this fix will need to be done to all IS500 is probably spot on.
I think we can safety say a Service Bulletin is gonna be a minimum, if not an actual recall.
As this is emission related, I think the recall will come.
If NTHSA gets involved, then for sure it's gonna be a recall.
I think we can safety say a Service Bulletin is gonna be a minimum, if not an actual recall.
As this is emission related, I think the recall will come.
If NTHSA gets involved, then for sure it's gonna be a recall.
#52
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I got my check engine light today. Around 100 miles on the car. Dropped it off at the dealership this evening and was told someone would be in touch tomorrow. Pretty ****ing annoyed. One of the biggest justifications for buying this car was Lexus reliability and here we are. I’ve owned multiple German cars and never had issues this early into ownership.
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wthrman2 (01-26-22)
#53
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I got my check engine light today. Around 100 miles on the car. Dropped it off at the dealership this evening and was told someone would be in touch tomorrow. Pretty ****ing annoyed. One of the biggest justifications for buying this car was Lexus reliability and here we are. I’ve owned multiple German cars and never had issues this early into ownership.
#54
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I got my check engine light today. Around 100 miles on the car. Dropped it off at the dealership this evening and was told someone would be in touch tomorrow. Pretty ****ing annoyed. One of the biggest justifications for buying this car was Lexus reliability and here we are. I’ve owned multiple German cars and never had issues this early into ownership.
But go ahead people. Keep buying them and putting on your PPF and ceramic before you know if you have a lemon or not.
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Brandonfu (01-27-22)
#55
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I have 70 miles or so since Sunday. I'm going to to call the dealer and ask them to expect me soon and order the gasket/sensor now so I don't have to wait around.
Think they'll tell me to pound sand?
Think they'll tell me to pound sand?
#56
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#58
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#59
#60
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I felt the same way. In fact, you simply cannot say that the IS500 is reliable at this point. Think about this: I will never be able to tell people, “I’ve NEVER had a problem with this car.” It’s a shame. These engines might be “bulletproof,” but the electronics and car as a whole are not immune to issues more than any other car manufacturer.
But go ahead people. Keep buying them and putting on your PPF and ceramic before you know if you have a lemon or not.
But go ahead people. Keep buying them and putting on your PPF and ceramic before you know if you have a lemon or not.
Last edited by TipsyTonio; 01-26-22 at 08:41 PM.
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Carolina50 (01-28-22)