P1155 code confusion

[P1155ed]

I have this fault code and there appears to be disagreement between sources about what it is, for example:

http://www.troublecodes.net/toyota/camrycelica-corolla-matrix-mr2-paseo-rav4-tercel-1995-2009/  -  Heated oxygen sensor (H02S)- RH front- heater circuit malfunction

https://www.obd-codes.com/trouble_codes/toyota/ - air/fuel sensor (bank 1 sensor 2)

https://www.engine-light-help.com/toyota-check-engine-light.html - Air/Fuel Sensor Heater Circuit. (Bank 1 Sensor 2)

which all points towards it being bank 1, sensor 2, however the following:

https://www.toyotanation.com/forum/135-corolla-lounge/148676-obd-ii-trouble-codes-full-list.html - A/F Sensor Circuit Response Malfunction (Bank #2 Sensor #1)

https://parts.olathetoyota.com/p1155-code - Faulty air/fuel ratio sensor in bank 2, sensor 1

plus various other posts I've seen on forums point towards P1155 being bank 2 sensor 1.

So clearly it is either bank 1 sensor 2 or bank 2 sensor 1 and sombody has made a transcription error somewhere but which one is?

Does anybody have access to an authorative source that can give the right answer?

[P1155ed]

I've performed a little test and have come to the conclusion that code p1155 refers to bank 2 sensor 1.

I disconnected bank 1 sensor 1 and this generated the code 1135, Toyota Nation indicates this is " A/F Sensor Heater Circuit Malfunction (Bank #1 Sensor #1)", which is what I disconnected, Troublecodes (real trouble) indicates "Heated oxygen sensor (H02S) – heater circuit malfunction", which would assuming any logic in the numbering and description system indicate the LHS version of what they think is bank 1 sensor 2 i.e. b2,s2 (nope).

The situation becomes a bit more apparent when you notice that odb-codes and engine-light-help describe the fault as "air/fuel sensor bank 1 sensor 2". but the air/fuel sensor is always sensor 1, sensor 2 is the oxygen sensor and while the terms are sometimes used interchangably for the a/f sensor, describing an oxygen sensor as a/f would be strange.

One final clue is that there are generic oxygen sensor codes used by all manufacturers (0130-0170) but codes above 999 are manufacturer specific, so a bank 1 sensor 2 heater malfunction would be p0141, but a p1135/p1155 code is not a generic oxygen sensor but instead a Toyota developed a/f sensor with its own special code, which is to say sensor number one.

I could be wrong, I'll update the thread to let you know how it works out.

[gjnorthall]

P1155 is bank 2 sensor 1. You are correct in your interpretation of generic OBD codes and manufacturer specific codes. Terminology can sometimes be confusing - all Lambda sensors measure oxygen - the reference to a/f is simply that no1 sensors measure oxygen in order to control the air / fuel ratio. There are many anomalies in tabulations of manufacturer codes - stick to UK published data if possible. As far as heater circuits are concerned - it's easy to confirm the location of the faulty sensor - measuring the resistance of the heater (the two black or two white leads) would indicate open circuit.