Code P1135 Air/fuel Ratio Sensor Heater 2001 Es300

[Ron T.]

Does anyone know where the air fuel ratio sensor , bank 1 sensor 1 is located. Some of the posts I've read say it's on the intake manifold others say it's on the exhaust manifold. I'm getting a P1135 code and might have to replace the sensor. Knowing on which manifold and exactly where would be a great help. Thanks in advance!

[George_Jetson]

o2sensor_check.pdf

The Air fuel sensors are located on the exhaust manifold. Bank 1 is the rear bank (next to the firewall, and a pain to get to). sensor 1 is the one closest to the head, attached is a pdf that shows how to measure the heater resistance. I would recomend ohming out the heater before you they to replace it.

o2sensor_check.pdf

[Ron T.]

Thanks for the info. and the pdf. Sounds as if you're familiar with this problem. I'll check the resistance and report back.

[George_Jetson]

It probably is the sensor, but it could also be a fuse, wiring or a relay. Sometimes the sensors get rusted into place and are difficult to remove. It is worth the effort to measure the heater to verify that is indeed the problem before you attempt to remove it. Especially the rear one (I replaced both main sensors on mine a few weeks back). Front one is easy, rear one is a pain.

[Ron T.]

Hey,

I looked at the sensor tonight. Didn't get a chance to ohm it yet. But, it looks like it would have to be changed from above if it needed replacing. Can you tell me what size wrench it takes? I assume a box wrench is the only way to go. Does the wiring connector fit through the wrench end? If it turns out to be a fuse, can you tell me where it is located? Thanks again!

[George_Jetson]

There are two different mounting styles. I have a 93, and it uses a flange with two studs, 12 mm nuts. The other style has the sensor threading into the manifold with a 7/8 or 22 mm nut (they make a special socket, but on most cars a box end wrench works fine. On most cars I have worked on the connector does fit thru the box end wrench (used to work on cars professionally, so I have replaced a few).

If you are good with a soldering iron, you could purchase universal sensors, and solder the old connectors onto the new sensors. Many people prefer Denso, I personnelly prefer Bosch. You can buy them on ebay much cheaper than from Toyota, or Lexus.

[Lexlogic]

There are two different mounting styles. I have a 93, and it uses a flange with two studs, 12 mm nuts. The other style has the sensor threading into the manifold with a 7/8 or 22 mm nut (they make a special socket, but on most cars a box end wrench works fine. On most cars I have worked on the connector does fit thru the box end wrench (used to work on cars professionally, so I have replaced a few).

If you are good with a soldering iron, you could purchase universal sensors, and solder the old connectors onto the new sensors. Many people prefer Denso, I personnelly prefer Bosch. You can buy them on ebay much cheaper than from Toyota, or Lexus.

Here is a link Sensor

[Ron T.]

I inspected the sensor the other day and moved the wires a bit, preparing myself for the task ahead. Strangely, after driving about 100 miles, the engine light hasn't come on again. I can only conclude that there is a loose or broken wire to the sensor.

Any thoughts?

[George_Jetson]

I would still suggest measuring the resistance of the heater. That will also give you a chance to inspect the connector, and reseat the connection, (could just be a little corrosion on the connector).

[Ron T.]

Sounds like good advice. The engine light hasn't gone on since I fooled with the wires. Might just be a dirty or corroded connector as you suggest. I'll check it out and report back. Thanks!

[flanso]

I recently changed the bank 1, sensor 1 on my 2001 ES300 after getting the P1135 code. I didn't bother to check the heater circuit resistance because the car has about 100k miles and that appears to be the mileage when these sensors fail. The lowest price I could find was from Amazon.com, $132 for a Denso, which is the brand I much prefer. The problem with the Amazon site, though, is it does not know what sensor fits what. When I searched Amazon by application, I had no luck. I went to the Denso site, found their part number for my ES300 and then searched that part number on Amazon, which they had. By the way, near the firewall on the driver's side, there is an 8 or 10 inch, tubular brace that goes from the intake manifold to the block held on by two bolts with 10 mm heads. Taking off that easily-removable brace gave me a lot more room to get to the sensor and its connector.

[Ron T.]

Hi Everyone,

I finally got around to changing that sensor. I bought a Denso from Amazon also. It was $123.00 and free shipping. Only one arm fits in the space so disconnecting the connector is a bit of a trick with one hand but not impossible. The 7/8 box wrench did the trick. A few pulls and it came free. After installing the new one I ran the engine for about 20 min. The engine light remained on until I shut it off and re-started it a short time later. The engine light is now off. Job done!

Thanks all for your help!

Happy New Year!

Ron

[George_Jetson]

Glad to hear it worked out well. You will know for sure after a few engine cycles. Do not be concerned about the light remaining on immediately after you replace it. The check engine light will remain on until the computer has verified that the sensor is working correctly. In the case of a A/F sensor, this includes waiting until the engine and the sensor has reached temp.

[Lexlogic]

Does anyone know where the air fuel ratio sensor , bank 1 sensor 1 is located. Some of the posts I've read say it's on the intake manifold others say it's on the exhaust manifold. I'm getting a P1135 code and might have to replace the sensor. Knowing on which manifold and exactly where would be a great help. Thanks in advance!

Behind the radiator between engine on the exhaust manifold before it curves down to the cat. oxygen sensor