Air-Fuel Ratio (A/F) Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
- Thread starter vipblades
- Start date
The air fuel ration sensor indicates the error codes were 1135 and 0125. Inside the store, they can look up the codes on their computer. Assuming you always add a P to the code, they are:
P1135: "Pedal position sensor A circuit intermittent".
P1135: "Pedal position sensor A circuit intermittent".
YarSmythe
New member
My experience
Wanted to share my recent experience in the hopes it might assist another.
2002 4Runner SR5 Sport Edition, California emissions
After the first Check Engine Light (CEL), I took it to the local auto parts store and got a P0420 code (bad CAT). My dealer also confirmed the same code when I took it to them. Neither mentioned replacing the A/F sensors. Only that I'd have to replace my converters. I didn't like this option so they opted to reset the codes and recommended I try Seafoam in the tank to 'clean the CAT'. I tried it and I had no CEL for a month. Then it returned.
At this point I figured I was going to pay for new catalytic converters ($$$) but the dealer reset the code again and had me repeat the Seafoam cleaning. "Sometimes it takes a while", they said. Sadly, a month later, I got the CEL again.
THIS time, I took my truck to a Meineke Muffler store nearby and they said the code was a P1135. The owner was super cool and said he felt it was the forward A/F sensor. He suggested I go buy one at a local store (cheaper) and then he'd install it for $50.
After reading several great threads on this website, I took the advice of many and bought BOTH sensors on Amazon.com. Here are the Denso sensors I bought:
Denso 234-9002 (Forward)
Denso 234-4261 (Rear)
I decided to install these myself as it appeared access was very simple. None of my bolts were in poor condition and they ended up coming over very easily. (see pics of originals)
After installing these sensors I am happy to report that I have not had a CEL light for over a month (also passed inspection!). I also think my mileage has improved a little. (I get around 300 miles per tank)
Today I installed a new fuel and air filter to top off this mini tune-up. I was surprised as many others here when Toyota says the fuel filters do not need to be replaced. I pulled mine out and dumped out a TON of crud from the original filter. I highly recommend you replace your fuel filter ($23) if you have over 100K miles. It is not difficult to do. Even if I don't see an improvement in gas mileage, I will drive a little happier knowing my engine is being treated with cleaner gasoline.
Thanks to all of you who are posting comments and modifications to their 4Runners. This is my third 4Runner with 134K miles...and runs great.
-Lee
Wanted to share my recent experience in the hopes it might assist another.
2002 4Runner SR5 Sport Edition, California emissions
After the first Check Engine Light (CEL), I took it to the local auto parts store and got a P0420 code (bad CAT). My dealer also confirmed the same code when I took it to them. Neither mentioned replacing the A/F sensors. Only that I'd have to replace my converters. I didn't like this option so they opted to reset the codes and recommended I try Seafoam in the tank to 'clean the CAT'. I tried it and I had no CEL for a month. Then it returned.
At this point I figured I was going to pay for new catalytic converters ($$$) but the dealer reset the code again and had me repeat the Seafoam cleaning. "Sometimes it takes a while", they said. Sadly, a month later, I got the CEL again.
THIS time, I took my truck to a Meineke Muffler store nearby and they said the code was a P1135. The owner was super cool and said he felt it was the forward A/F sensor. He suggested I go buy one at a local store (cheaper) and then he'd install it for $50.
After reading several great threads on this website, I took the advice of many and bought BOTH sensors on Amazon.com. Here are the Denso sensors I bought:
Denso 234-9002 (Forward)
Denso 234-4261 (Rear)
I decided to install these myself as it appeared access was very simple. None of my bolts were in poor condition and they ended up coming over very easily. (see pics of originals)
After installing these sensors I am happy to report that I have not had a CEL light for over a month (also passed inspection!). I also think my mileage has improved a little. (I get around 300 miles per tank)
Today I installed a new fuel and air filter to top off this mini tune-up. I was surprised as many others here when Toyota says the fuel filters do not need to be replaced. I pulled mine out and dumped out a TON of crud from the original filter. I highly recommend you replace your fuel filter ($23) if you have over 100K miles. It is not difficult to do. Even if I don't see an improvement in gas mileage, I will drive a little happier knowing my engine is being treated with cleaner gasoline.
Thanks to all of you who are posting comments and modifications to their 4Runners. This is my third 4Runner with 134K miles...and runs great.
-Lee
Attachments
Yoda4runn3r
New member
YarSmythe thanks so much for your pix w/ this post. I had the dash light up like a Christmas tree and was told by a dealer it was the Air Fuel sensor 1 Bank 1 also. They wanted A LOT to replace it. That said I just ordered the sensor from - Underdog Racing Development. Got the part inc. shipping for less than $170. My only confusion was I thought the dealer told me there were two AF sensors and two o2 sensors (one each on bank one and one each on bank 2) does that sound right? If so which are the bank 1 sensors? Also, I have not gone under the car to look yet but about where are the sensors located on the exhaust? Thanks again!
help!
yes, I have the right part for my truck "Denso 234-9001" (2000 4Runner 3.4 L V6 Cali emissions, manual tranny)
yes, I unscrewed the two bolts and the sensor came out without any fuss.
NO, I can't disconnect the silly electrical connector located on top of the tranny!
I know I should use a small flat head screwdriver to push the lock/latch, but without seeing the connector I just don't know how. yes, I can "see it" with my fingers but I have no clue how it latches.
Is there any image available, or description of the bloody thing so I can figure out where to place the tip of screwdriver?
Thank you in advance for your time and help!
yes, I have the right part for my truck "Denso 234-9001" (2000 4Runner 3.4 L V6 Cali emissions, manual tranny)
yes, I unscrewed the two bolts and the sensor came out without any fuss.
NO, I can't disconnect the silly electrical connector located on top of the tranny!
I know I should use a small flat head screwdriver to push the lock/latch, but without seeing the connector I just don't know how. yes, I can "see it" with my fingers but I have no clue how it latches.
Is there any image available, or description of the bloody thing so I can figure out where to place the tip of screwdriver?
Thank you in advance for your time and help!
P1135 & c1201
I'm new to forums and this board so I hope I'm posting this in the right place, and I really hope I get some responses quick
.
My VSC, VSC TRAC and Check Engine lights all came on last week so I went to have the codes pulled.
P1135 - Air / Fuel Sensor Heater Malfunction - Bank 1 Sensor 1
AND
C1201 - Engine Communication Circuit
I had this problem a few years ago and had to have an 02 sensor replaced - at the dealership - and it cost me over $300.
What do I do? Is the Air / Fuel Sensor the same thing as an 02 Sensor?'
Thank you for any and all advice!!
Heather
2001 Toyota 4Runner SR5 / 4WD
Wilmington, NC
I'm new to forums and this board so I hope I'm posting this in the right place, and I really hope I get some responses quick
. My VSC, VSC TRAC and Check Engine lights all came on last week so I went to have the codes pulled.
P1135 - Air / Fuel Sensor Heater Malfunction - Bank 1 Sensor 1
AND
C1201 - Engine Communication Circuit
I had this problem a few years ago and had to have an 02 sensor replaced - at the dealership - and it cost me over $300.
What do I do? Is the Air / Fuel Sensor the same thing as an 02 Sensor?'
Thank you for any and all advice!!
Heather
2001 Toyota 4Runner SR5 / 4WD
Wilmington, NC
TheDurk
Elite Member
I'm new to forums and this board so I hope I'm posting this in the right place, and I really hope I get some responses quick
My VSC, VSC TRAC and Check Engine lights all came on last week so I went to have the codes pulled.
P1135 - Air / Fuel Sensor Heater Malfunction - Bank 1 Sensor 1
AND
C1201 - Engine Communication Circuit
I had this problem a few years ago and had to have an 02 sensor replaced - at the dealership - and it cost me over $300.
What do I do? Is the Air / Fuel Sensor the same thing as an 02 Sensor?'
Thank you for any and all advice!!
Heather
2001 Toyota 4Runner SR5 / 4WD
Wilmington, NC
A P1135 is definitive and unambiguous. You need a Denso 234-9002 Air/Fuel Sensor which is the same one Toyota will install for $300. Best price is usually on Amazon--a little over $100. Install it yourself and save $200. Your truck has two exhaust sensors, an Air/Fuel sensor in front of the cat and an O2 sensor after it. The A/F does the same thing as the O2, it is just more advanced technology--and also more expensive.
Amazon.com: Denso 234-9002 Air Fuel Ratio Sensor: Automotive
thanks for posting this... I got the p1135 code, cleared it out and it came back on so i ordered the part posted above, searched around for a tutorial and couldn't find one, then i read some amazon reviews and realized it was literally 2 12mm screws and one 10mm screw for the wire harness. super easy to do
TheDurk
Elite Member
Be careful when you do that. I took into account his year, transmission, engine, and whether or not he was a Cali. type when I gave that number. You lucked out if it was correct.
