O2 senser heater malfuntion Bank #1

[DOUGLASNC]

Hi, Just did timming belt replace and went for test drive. Check engine light came on.My OBD2 said the O2senser heater malfuntion on bank #1 Did it go bad that fast, or could i have done something while replacing the timming belt and waterpump ect.I did have the main plug with the 10mm bolt holding it togeather loose, and the other plugs in that area; but the O2 senser is on the other side of the engine.Oh, i also re-placed the air filter and took the hose loose at the maf. senser along with some smaller hoses to give my more room .But i feel a got them all back togeather . Any thoughts? I read that the heater in built in the O2 senser and the O2 senser has to be replaced to fix this. Is this correct? Thanks Douglas

[tempfixit]

Welcome to AF.

What year vehicle, mileage, engine?

Would you give us the code # please.

Probably just a coinsidence that it failed at this time. Check to make electrical connector is clean of corrision and tightly secrued.

Bankl # 1 is the bank closest to the firewall so I don't believe you did anything wrong but never hurts to double check yourself.

Life of a 02 sensor is normally around 100.000 miles.

Keep us posted.
In the forum look for the Free Online Factory Service Manual thread, there is a procedure in there to test the 02 sensor.

[DOUGLASNC]

Thanks for the welcome and for the quick reply. Sorry, it's a 99 mercury villager with the 3.3 engine. It's got 123,000 miles on it now, so i guess it's time to go out. you said that bank #1 is closest to the fire wall?Is that the one closest to the cat and muffler? I was thinking it was the one on the exhaust manifold on the front side of the engine nearest radiator. It would have to be the hardest to get to...lol I'll check out the repair threads you mentioned, and thanks again for your help.Love to read all the post, and i hope i'll be able to help someone out as you have helped me...Great site! Thanks,,Douglas

[tempfixit]

The code number will indicate if it a upstream sensor (before cat) or downstream sensor (after cat). Go to the Online FSM it has testing procedure that are code specific in the EC Section, before you replace the sensor.

I forgot to mention that Number 1 bank is always side that the number 1 Clyinder is on, in this case closest to firewall.
Closest to firewall clyinders are 1,3,5
radiator side are 2,4,6