O2 And A/f Sensors

[way2007]

hello,

i have a 99 es300 , are o2 and a/f sensor same ? iam getting p1135 and trying to replace one of the 02 sensors.

I know there are 3 o2 sensors on the 99 es300 model. But are they all same 02 sensors, meaning can i use the o2 sensor from the firewall area(is that bank1 sensor 2) to replace the one from the front. i recently bought a 02 sensor from a junkyard . The guy pulled the o2 sensor from the firewall area . so i am wondering if i should put this on the front at bank1 sensor 1.

I already replaced the MAF and now i get p0125. when i use a odb reader it says cant get the readings on 02 yet. i recently unplugged/cleared the code after replacing the MAF. It appears my car hasnt run full yet to get the o2 readings.

Any thoughts?

appreciate much.

thanks

[Loyal_Lexinator]

hello,

i have a 99 es300 , are o2 and a/f sensor same ? iam getting p1135 and trying to replace one of the 02 sensors.

I know there are 3 o2 sensors on the 99 es300 model. But are they all same 02 sensors, meaning can i use the o2 sensor from the firewall area(is that bank1 sensor 2) to replace the one from the front. i recently bought a 02 sensor from a junkyard . The guy pulled the o2 sensor from the firewall area . so i am wondering if i should put this on the front at bank1 sensor 1.

I already replaced the MAF and now i get p0125. when i use a odb reader it says cant get the readings on 02 yet. i recently unplugged/cleared the code after replacing the MAF. It appears my car hasnt run full yet to get the o2 readings.

Any thoughts?

appreciate much.

thanks

On my 98' The part numbers come up the same for the 2 before the cat. the one after the cat came up as a different part number. There seems to be some confusion on which is bank1 and bank 2 however.... When i had Autozone pull the codes for me it came up as bank1 sensor1, and they pulled up their diagram, and it showed it to be the one at the front of the car. I have also read in the forum here that it is the front one. However, I downlaoded the Field Service manuals, and was browsing through the service bulletins, and it shows Bank1 Sensor1 to be the one between the firewall and the engine.... The reason i went through all of the searching, was that after replacing the front O2 sensor, nothing changed. The codes came right back up. So after researching, I found this info, and tried changing out the one between the firewall and engine.... i have about 500 miles on in now, and no check engine lite...

Hope this helps.... If someone can verify what i found that would be great...

Ron

[steviej]

Air fuel sensors are usually between the exhaust manifold and the catalytic converter.

O2 sensors are usually after the cat.

They may be the same part number but the signal given off to the ECU may be different.

[way2007]

Air fuel sensors are usually between the exhaust manifold and the catalytic converter.

O2 sensors are usually after the cat.

They may be the same part number but the signal given off to the ECU may be different.

Thanks Steviej and All for helping me out.

I was able to replace B1S1 near the firewall on my 1999 es300 within 15 mnts. i did have the o2 sensor that i rented from Autozone. But i was able to use a regular 7/8 wrench to remove it . It was more easier for me and my hands were easily accessible to it. In my case it was a A/F ratio sensor and I bought it from ebay for 143$.

i had recd p1135, p0171 and p0172 enitially, after i took the old sensor out cleaned the end and put it back , i still continued to see the error code p1135and now p1133 and p0125.

once i replaced the sensor on b1s1 ,cleared the error codes, started the car, what a difference in the RPM. I always thought the RPM i had was a little higher than normal . before replacing the sensor It used to be at about 1500 -2000 when i start the car and idling, but would come down to 800-1000 when i change the gear. I had also noticed higher rpm at 2500 when driving at 50 speed.

After changing the sensor i noticed the RPM was at 1000 when i start and emmidiatly it came down within 500-1000 when idling.

Also i noticed i was now going at 60-65 at 2500 rpm. Hope these above observations are normal for this car. ?...

I havnt seen any codes yet. I do have a scanner and i was able to see all the emmision codes (CC, O, OH) finish scanning and no error codes yet after driving 30 miles at 50-65 mph. I still have the (EV) yet to finish its course. I hope that wont cause my emission to fail.

Since i have a emission test to be completed by tomorrow(failed once earlier) , i was told that any one of the 3 (cc,o, oh, EV) ? needs to cleared to pass the test.

Thanks again for all your help. Next is to see what is causing my car to leave one or 2 oil drops in my garage every 2-3 days.I hope you all will continue to help me learn more about my car and how to fix it.

[steviej]

valve cover gaskets and rear main seals are know culprits of oil leaks on the ES.

If it is the rear main seal...that means $$$$. Before you do that you could try a thicker oil. If you are using a 5W or 10W-30 you could go to a 10W-40 which may stop or slow the leak for a while.

If it is the valve cover gaskets, these are an easy fix. Since these are above the exhaust manifold, this leak is usually accompanied by a buring oil smell.

steviej