2002 Avalon O2 Sensor P1155 Code

[garagedude]

New guy here - HELLO TO ALL. Have P1155 code - heat ckt. O2 sensor bank1, sensor 1. Replaced, still have code. Used equiv. DENSOR sensor. Will these work or do I need to buy Toyota part? Details below - can anyone provide me direction as to what to try next?
garage dude - although will be EX-garagedude if I don't fix this mess!!!!
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1. Check engine light on – code read was:
P1155 AIR/FUEL SENSOR HEATER CIRCUIT RESPONSE BANK 1 SENSOR 1.

2. Ordered DENSOR model 234-9021 Oxygen Sensor (same as Toyota part 89467-41040), installed
new unit. Reset the DTC’s. Started engine. Check Engine OFF, but came back on after about 15 seconds. Code P1155. Per procedure in repair manual page SF-79, checked resistance of heater circuit in removed oxygen sensor. Circuit is open, rather than the 0.8 – 1.4 ohm specified in manual. So the removed oxygen sensor is bad.

3. Also saw P1135 – Heater Circuit Bank 1 Sensor 2. Ordered DENSOR model 234-4061 Oxygen Sensor (same as Toyota part 89465-07040 Denso 0571), installed this new Bank 1 Sensor 2. Check engine light still on P1155
4. Heater circuit check is for current draw is range from .5 amps to 8 amps. Possible short in heater circuit, so I checked all applicable fuses - - - none blown.
5. Removed and checked the A/F Sensor Heater Relay per instructions on page SF-61 section 3 & 4. Relay tests OK, so re-installed relay.
6. Since I reset diagnostic trouble codes (DTC’s) during these procedures to verify fix, the reset also
reset the status of the I/M System Monitors to “NOT READY”. Even after driving for days, the following are still showing as NOT READY;
- - CATALYST
- - Evaporator System
- - O2 Sensor
Note – gas mileage has remained excellent during all of this, so it seems like EFI system is running OK – just the heater circuit for fast passage from OPEN LOOP operation to CLOSE LOOP Operation is screwed up.
I don’t know what the status of these were before I did the first reset of the DTC’s.
At this point I don’t know what else to check. Anyone have any ideas????

[cs2634]

i have a 01 avalon and am getting p1155 -alternative fuel controller,i was told it means my af sensor left side is bad,can anyone tell me how i can check this and where it is,i think its the one in the front exhaust manifold by the radiator,also its $206 at the dealer,any place else u can get it ?thanks

[TS Support]

Code P1155 is A/F Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
Trouble Areas:

Open or short in heater circuit of A/F sensor

sensor heater

ECM

[garagedude]

I AM IMPRESSED!!!! THANKS FOR INFORMATIVE INFO!!!
I had codes P1155 and P1135 (Bank1 sensor 1 at rear of engine, and Bank 1 sensor 2 after cat. converter.) Replaced both - still code P1155. Checked Bank 1 sensor 1 heater ohmeter check - open circuit - so this was part of the problem.
Was ready to give up then tested Bank2 sensor 1 at front side of engine - IT ALSO HAD AN OPEN HEATER. One must have failed, but didn't get error until both failed and fell out of the range of .25 amps to 8 amps. Replaced the front sensor as well, and all is OK.
Unfortunately the P1155 and P1135 error codes are misleading as no mention of front sensor.
Glad it was sensor and not wiring or the ECM.
Thanks again for your help.
Guy who asked where to buy sensors cheaper than dealer - Toyota uses DENSO sensors - do a google search for Oxygen Sensors - you will get plenty of sites that sell these for about $180 engine sensors, and $93 for one by cat. converter. They are fairly easy to remove and test with ohm meter for heater coil in sensor.

[garagedude]

I will post here my procedure for fixing problem with my 2002 FYI to all interested. comments/suggestions?????
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The error code P1155 and P1135 and resulting check engine light is due to failure of one or more A/F Sensors (Air/Fuel sensor, or sometimes called Oxygen Sensor). There are three in my 2002 Avalon. There are two parts to the sensor - a heater that heats up the sensor quickly, and the Oxygen sensing part. The error code says you have a problem with the heater. Your mileage after warm up should be normal if O2 part is working OK. If you get consistent bad mileage, I would get it fixed ASAP as an over rich mixture will shorten the life of the CAT converter.
SENSOR TYPES (at least on my 2002)
Bank2 Sensor 1 - front of engine exhaust manifold
Toyota part 89467-41040 by DENSO. OEM equiv. Denso 234-9021
Heater resistance check at 68 degrees F 0.8 to 1.4 ohms
Bank 1 Sensor 1 - rear engine exhaust manifold
Toyota part 89467-41030 by DENSO. OEM Equiv. DENSO 234-9021
Cost of these about $180 each - find via google search. Toyota price
about $230 each.
Heater resistance check - same as above
Bank 1 Sensor 2 - under car in back of Catl. Converter, Connecter under
passenger front seat.
Toyota part 89465-07040 by DENSO. OEM Equiv. DENSO 234-4061
OEM part costs about $83.
heater resistance check at 68 degrees F. 11 - 16 ohms.
You need to unplug each sensor, and test resistance reading between the two terminals in sensor plug that have the two black wires into plug. This will check if the heater in the sensor is open or shorted. Resistance readings are as shown above. You will probably find one or more that have failed. I had two out of three bad!!!!
The front sensor - easy to get to and remove. The rear one - you can fish your hands down from the top to unscrew and disconnect. The one by the cat. Converter - remove four bolts holding passenger seat, lean it back out of your way. Pull carpet out from under the plastic on the center console, pull out as best you can, you will see the sensor connector and the wires coming through the floor board. Disconnect the connector, and push the rubber grommet out the hole - then you should be able to unscrew the sensor.
You are on your own using OEM. I did but only have one day on them. This procedure is a guide only - you are on your own. One needs to be fairly mechanical to pull this off... Good luck. Hope this helps……