98 Taurus fault code P0155

My car just popped a code of P0155. It is the "upstream heated O2 sensor heater circuit fault (bank 2). Could someone help me with this? I do not know what bank 2 is. Does the fault mean the O2 sensor is bad? My books do not tell me anything about it except how to replace and I know ho wto do that. Just do not know which of the four to change out. Any info would be greatly appreciated. Thanks

Bank 1 is the front or radiator side of the engine, bank 2 is the rear or firewall side. Up stream is before the catalytic converter, down stream is past the converter. The upstream are usually the first to go.

I have taken them out and give them a good cleaning with carburater cleaner and a brush, blow them out with forced air, put them back in, and solved the problem. Worth a try, cheaper than a $60 - O2 sensor!! Sometimes the wiring connecters get dirty also.

Ron

Thans for that info Ron. One more question thoug. Do you have to get to it from under the car or can I get to it from the top side? Not much room on the top from what I remember changing plugs. thanks again for the tip. Now I know 1 and 2. Appreciateit very much.:grinyes:

That's a flat of your back job! Provided you don't have access to a lift. Be sure to use good jack stands!!

Ron

Thanks! I wil let you know ho weverything turns out. I am going to attempt your way first. If I can save some duckies I am all for it. I do get a 25% discount on psrts but still free is better. Thanks again!

Bank 1 is the front or radiator side of the engine, bank 2 is the rear or firewall side. Up stream is before the catalytic converter, down stream is past the converter. The upstream are usually the first to go.

I have taken them out and give them a good cleaning with carburater cleaner and a brush, blow them out with forced air, put them back in, and solved the problem. Worth a try, cheaper than a $60 - O2 sensor!! Sometimes the wiring connecters get dirty also.

Ron
You've got that backward. Bank 1 is the bank nearest to the firewall (cylinders 1-3). Bank 2 is the bank just behind the radiator. If you are standing just in front of the car, bank 2 is nearest you (and the front of the car) and bank 1 is the furthest from you. Cylinder #1 is the cylinder nearest the pulleys and serpentine belt of bank 1, cylinder #2 is the rear middle cylinder (bank 1) and cylinder #3 is the cylinder on the right end of bank 1. Bank 2 starts with cylinder #4 nearest the serpentine belt. It's like reading a book, left to right, top (furthest away) to bottom (nearest you).

Per the factory service manual, typical causes of a P0155 code can be as follows:
-- Shorts to VPWR in harness or HO2S.
-- Water in connectors.
-- Cut or pulled wires.
-- Disconnected wiring.
-- Open VPWR circuit.
-- Open GND circuit.
-- Low battery voltage.
-- Corrosion or poor mating terminals.
-- Damaged HO2S heater.
-- Damaged PCM.

-Rod