Hi everyone wondering if someone can help, last month got a codes for bank 1 sensor 2 o2 sensor heater control circuit and on data showed no voltage at plug which I tested. Replaced and ran fine for 1 month now code is back on ? Now there is voltage showing at data so I'm abit lost has anyone seen this before ? Thanks

Should of added it is 65 plate and done 21000 miles 

When you say voltage showing do you mean 02 output voltage?  That fault is for the heater circuit, not the 02 circuit.  If the heater coil has failed in the sensor then you'll get open circuit across the two heater wires.  If there's no heater input voltage from the car side then that suggests a wiring fault between the PCM and the 02 sensor heater.

Or a blown fuse. 

Fuse 17 in battery junction box.

Thanks for reply, sorry not too technically minded just got a cheap diagnostic that was showing voltage to a sensor haha. Gonna check it later and let you know. Fault kept coming back on when clearing after a few hours, changed sensor and it stayed out for about 1 month/ 650 miles and now is coming back on after clearing in a day. Do you think this could be faulty sensor or I have seen it could be a faulty cat? Is there any way to check this 

13 minutes ago, Anthony1997 said:

Thanks for reply, sorry not too technically minded just got a cheap diagnostic that was showing voltage to a sensor haha. Gonna check it later and let you know. Fault kept coming back on when clearing after a few hours, changed sensor and it stayed out for about 1 month/ 650 miles and now is coming back on after clearing in a day. Do you think this could be faulty sensor or I have seen it could be a faulty cat? Is there any way to check this 

It's definitely not the cat with that fault description. 

The sensor heater is literally just a heater coil inside the sensor, completely separate from it.  It's not taking any readings from the cat, it just heats up like a toaster element.  (Basically, the sensor relies on a chemical reaction which is more effective when warm, so modern ones are heated to make sure they work at maximum efficiency.)

If the sensor fitted was a cheap aftermarket one, then it may have failed again already.  Genuine lambda sensors are expensive, but do generally last longer.

It could also be that the wiring for the new sensor was left loose, and has now got burnt or rubbed on something, so that's definitely worth checking before replacing it.  Or could be the fuse, as Ian said.

Appreciate the response mate, was a bosch one so will see if there anything better happy to hear it's no cat haha. Will check it all later and let you know if I could pick your brain one more time haha could the fuel air mixture cause the sensor to fail premature? Or is it just a case of faulty sensor/ wiring pcm issue. Thanks

As above, the heater part has nothing to do with the cat, so the AFR won't affect it.

It would be worth double checking that fault code.  Without the code to confirm, we've only got your word for it being the heater in the fault description.

Bosch should be decent as long as it was genuine.  There is a small possibility of it being a fake.  So I would say it's probably a wiring fault now.

I see thanks for info, sorry didn't realise I hadn't put the code is p0036

Hi ian do you have diagram picture of fuse 17 location as I only have what Google offers and that is saying 17 is not used thanks mate 

15 minutes ago, Anthony1997 said:

have diagram picture of fuse 17 location

See Ford owners handbook, pages 188 and 189 for details.

https://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/ENUSA_CG3568_Focus_mxcd_og_201403.pdf

Perfect thanks mate, would never of got it haha 

33 minutes ago, unofix said:

See Ford owners handbook, pages 188 and 189 for details.

https://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/ENUSA_CG3568_Focus_mxcd_og_201403.pdf

That looks like a fuel fired aux heater for a diesel.  Not the lambda heater.  

1 minute ago, TomsFocus said:

That looks like a fuel fired aux heater for a diesel.  Not the lambda heater

No comment 🤣

@iantt told the Op to check fuse 17, and the Op asked where it was. Perhaps that fuse supplies more than one circuit?

Seems like maybe 32 ? But none of other stuff seems to be affected however will check anymore, thanks to your helps seem like sensor is either faulty which is gonna be replaced or wiring issue. Thanks everyone 

32 minutes ago, unofix said:

No comment 🤣

@iantt told the Op to check fuse 17, and the Op asked where it was. Perhaps that fuse supplies more than one circuit?

I will go and recheck. 

1 minute ago, iantt said:

I will go and recheck. 

I've fallen in to this trap before. If you get the fuse number from the Ford schematics they are very often not the same number as those shown in the owners handbook. It must be a a Ford thing 🤣

2 minutes ago, unofix said:

I've fallen in to this trap before. If you get the fuse number from the Ford schematics they are very often not the same number as those shown in the owners handbook. It must be a a Ford thing 🤣

Can be wrong both ways. 

Fuse 17 according to wiring diagram 

Probably not the fuse if he only getting 1 DTC. Fuse supplies both sensors , so back to either wiring fault or faulty new sensor. 

29 minutes ago, iantt said:

Fuse supplies both sensors , so back to either wiring fault or faulty new sensor. 

That would seem to be the case 👍

Or the wrong sensor has been replaced, so the original problem is still exists.

Thanks for all your input I'll check this all and get back to you👍

Hi everyone so tried a new sensor and drove fine however after 1 day same code came back, so seem like a pcm or wiring issue what is it I have to check and where ? Thanks 

The heater wiring needs to be tested from the plug on the O2 sensor, all the way to the plug on the PCM (engine ECU).  

Right looks like it's a auto spark job haha thanks for all info