Toyota AFR / 02 Sensor Problems
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Date: 2020-08-05
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Comments and reviews: 10
scientist100
Eric, thanks for the help. I have a Toyota Sienna 2007, though in my case, if I run at idle, AFS stays at 3. 29 like in your case but when I accelerate and stop, it will drop all the way to zero and it will slowly ramp up to 3. 29, only one time I saw it stay below 3 on one of them but it came back after the second throttle. I was watching the Long and short terms, when it is at idle, I see 7. XX & 10. XX (Long FT, when I accelerate and keep it, it stays at around 3 for both of them, when I accelerate just a little bit and keep it, it stays 4 & 7; the change is instant. I was thinking of a vacuum or bad data from the MAF but when I accelerate and decelerate, I see the MAF responding very well. The reason I'm concerned about the AFS is because at some point I did have a code on it but I would reset it and it would not come back until several months later. I did notice that the exhaust gets a little hotter over time because I can hear the cooling down noise lol. Please let me know what you think in this case. I currently have no codes stored.
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Eric, thanks for the help. I have a Toyota Sienna 2007, though in my case, if I run at idle, AFS stays at 3. 29 like in your case but when I accelerate and stop, it will drop all the way to zero and it will slowly ramp up to 3. 29, only one time I saw it stay below 3 on one of them but it came back after the second throttle. I was watching the Long and short terms, when it is at idle, I see 7. XX & 10. XX (Long FT, when I accelerate and keep it, it stays at around 3 for both of them, when I accelerate just a little bit and keep it, it stays 4 & 7; the change is instant. I was thinking of a vacuum or bad data from the MAF but when I accelerate and decelerate, I see the MAF responding very well. The reason I'm concerned about the AFS is because at some point I did have a code on it but I would reset it and it would not come back until several months later. I did notice that the exhaust gets a little hotter over time because I can hear the cooling down noise lol. Please let me know what you think in this case. I currently have no codes stored.
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ed
check A/F(air fuel)heater (not the Heater that keeps your feet warm) relay first. I swapped it with the horn relay, same part number on some cars/trucks and reset the check eng light and it was good. I just wasted 160 dollars on a o2 sensor that was still good. I fixed this with a 15 dollar horn relay. use a quality part like Denso or something. Beep check the same color wires(usually black on Toyota) on the 02 sensor with a ohm meter first before you waste money. I think it was P0031 Oxygen Sensor Heater Control Circuit Low Bank 1 Sensor 1or something like that
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check A/F(air fuel)heater (not the Heater that keeps your feet warm) relay first. I swapped it with the horn relay, same part number on some cars/trucks and reset the check eng light and it was good. I just wasted 160 dollars on a o2 sensor that was still good. I fixed this with a 15 dollar horn relay. use a quality part like Denso or something. Beep check the same color wires(usually black on Toyota) on the 02 sensor with a ohm meter first before you waste money. I think it was P0031 Oxygen Sensor Heater Control Circuit Low Bank 1 Sensor 1or something like that
reply
ed
check A/F(air fuel)heater (not the Heater that keeps your feet warm) relay first. I swapped it with the horn relay, same part number on some cars/trucks and reset the check eng light and it was good. I just wasted 160 dollars on a o2 sensor that was still good. I fixed this with a 15 dollar horn relay. use a quality part like Denso or something. Beep check the same color wires(usually black on Toyota) on the 02 sensor with a ohm meter first before you waste money. I think it was P0031 Oxygen Sensor Heater Control Circuit Low Bank 1 Sensor 1or something like that
reply
check A/F(air fuel)heater (not the Heater that keeps your feet warm) relay first. I swapped it with the horn relay, same part number on some cars/trucks and reset the check eng light and it was good. I just wasted 160 dollars on a o2 sensor that was still good. I fixed this with a 15 dollar horn relay. use a quality part like Denso or something. Beep check the same color wires(usually black on Toyota) on the 02 sensor with a ohm meter first before you waste money. I think it was P0031 Oxygen Sensor Heater Control Circuit Low Bank 1 Sensor 1or something like that
reply
Steady
Wow, you nailed it. Your voice even perked up when you figured it out. I commend you on your methodical troubleshooting. Finding an incorrect part installed by someone else can be a troubleshooting nightmare.
Also, you can use a 1lb propane cylinder with a std torch head to richen up the engine. Squeeze a length of hose on the torch end and put the free end in the air intake. Just crack the valve open and dont ignite the torch. You can fine tune how much added fuel you want to send into the engine. Great video, thanks.
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Wow, you nailed it. Your voice even perked up when you figured it out. I commend you on your methodical troubleshooting. Finding an incorrect part installed by someone else can be a troubleshooting nightmare.
Also, you can use a 1lb propane cylinder with a std torch head to richen up the engine. Squeeze a length of hose on the torch end and put the free end in the air intake. Just crack the valve open and dont ignite the torch. You can fine tune how much added fuel you want to send into the engine. Great video, thanks.
reply
Carl
I agree with wheel bearing just below me. I think this is one of the best videos Ive ever seen on YouTube about cars and I want to thank you for it. I have a 2004 Nissan Sentra with the 1. 8 L engine thats been driving me nuts with these two codes. P0011 Timing to far advanced and P004 20 the catalyst is below threshold whatever that means. Do you have any ideas what I can try? Or any idea? The cam sensor and crank sensor and the variable valve timing solenoid or all new. Thanks so much. Maybe one of your viewers can help me
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I agree with wheel bearing just below me. I think this is one of the best videos Ive ever seen on YouTube about cars and I want to thank you for it. I have a 2004 Nissan Sentra with the 1. 8 L engine thats been driving me nuts with these two codes. P0011 Timing to far advanced and P004 20 the catalyst is below threshold whatever that means. Do you have any ideas what I can try? Or any idea? The cam sensor and crank sensor and the variable valve timing solenoid or all new. Thanks so much. Maybe one of your viewers can help me
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Fredl
I have a California 2000 Toyota Sienna with 80, 000 original miles. I have hard time resetting the I/M readiness drive cyclemainly the CAT and EVAP. I took shots of the B1S1 AND B2S2 wideband AFR sensors voltage gragh readings. The B1S1 seems to fluctuate wildly from 1. 92 V to 4. 250V. It looks B1S1 is bad and needs replacement. Is it also possible I have a leaking exhaust Manifold. The B2S1 sensor reading is more steady at 3. 171v to 3. 176v.
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I have a California 2000 Toyota Sienna with 80, 000 original miles. I have hard time resetting the I/M readiness drive cyclemainly the CAT and EVAP. I took shots of the B1S1 AND B2S2 wideband AFR sensors voltage gragh readings. The B1S1 seems to fluctuate wildly from 1. 92 V to 4. 250V. It looks B1S1 is bad and needs replacement. Is it also possible I have a leaking exhaust Manifold. The B2S1 sensor reading is more steady at 3. 171v to 3. 176v.
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caiobabe
I learned so much from your video. Most importantly. The front sensor is NOT an O2 sensor but a air/fuel ratio sensor! I was about to change this sensor on my buddy's 03 Tundra as my scan tool gave me flat line readings and not a sine wave. Turns out, this is normal. You saved my friend 180 because that is what the Denso part cost. Took me half dozen YT vids to find the one that gave me the right answer and that was this video. Thank you!
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I learned so much from your video. Most importantly. The front sensor is NOT an O2 sensor but a air/fuel ratio sensor! I was about to change this sensor on my buddy's 03 Tundra as my scan tool gave me flat line readings and not a sine wave. Turns out, this is normal. You saved my friend 180 because that is what the Denso part cost. Took me half dozen YT vids to find the one that gave me the right answer and that was this video. Thank you!
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Alex
Hey, I have a Lexus RX300 that keep giving me the P1150 code every hundred miles or so. Recently I replaced the AF sensor (B2s1) and soon (100 miles or so) the code come back up. The replacement sensor I used was a Denso genuine sensor so it's unlikely a wrong sensor like what you had over there. But the code keep coming back. And there was no other codes. Any idea?
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Hey, I have a Lexus RX300 that keep giving me the P1150 code every hundred miles or so. Recently I replaced the AF sensor (B2s1) and soon (100 miles or so) the code come back up. The replacement sensor I used was a Denso genuine sensor so it's unlikely a wrong sensor like what you had over there. But the code keep coming back. And there was no other codes. Any idea?
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LTslimjim
I've got an AFR sensor on a Honda Fit 2007 I'm trying to diagnose in a similar method as you show, but the cheap scanner I have shows the current mA and not Voltage of the sensor. Can I use that in this test? From what I understand, it should have an increased current when lean and a negative current if rich. Thanks.
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I've got an AFR sensor on a Honda Fit 2007 I'm trying to diagnose in a similar method as you show, but the cheap scanner I have shows the current mA and not Voltage of the sensor. Can I use that in this test? From what I understand, it should have an increased current when lean and a negative current if rich. Thanks.
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DIY
I know you probably don't read too many comments on older videos, but just in case. This is a great educational video on AFR sensors and especially for a Toyota. I am a dumb DIYer and I learned a ton in how these wideband sensors work. Always appreciate Toyota videos - and BTW - what is Toyota Check Mode? Thanks, Eric!
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I know you probably don't read too many comments on older videos, but just in case. This is a great educational video on AFR sensors and especially for a Toyota. I am a dumb DIYer and I learned a ton in how these wideband sensors work. Always appreciate Toyota videos - and BTW - what is Toyota Check Mode? Thanks, Eric!
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