O2 Oxygen Sensor

[Theophilus]

An amber dashboard warning light has recently come on. Error Codes PO135 (O2 Heater Circuit Bank 1 Sensor 1) and PO141 (O2 Heater Circuit Bank 1 Sensor 2). Would appreciate advice on a couple of questions:

1] Why are BOTH failing at the same time?

2}Where are they located? My car is a K12 Micra C+C 2007.

 

[Sparky2018]

They are before and after the cat converter.
One is on the manifold and the other is on the exhaust down pipe or after second cat.

Probably one is triggering the other to show as an error.
Not gonna say I know if it's one or the other.
I would probably check manifold side tho.

 

[Theophilus]

Thanks for that Sparky. Is it difficult to get to the sensor on the manifold?

 

[Sparky2018]

Underneath will most likely be the best access. Manifold heatshield could be in the way.
Probably best method would be to warm up to temps as this may help with removal.
They are usually replaced with new also if that is required.
Although it might just be that one of the converters is blocked as this could cause the codes to show.
You maybe able to diagnose that via the exhaust if it seems restricted (flow) .?

 

[adrianblack]

Underneath will most likely be the best access. Manifold heatshield could be in the way.
Probably best method would be to warm up to temps as this may help with removal.
They are usually replaced with new also if that is required.
Although it might just be that one of the converters is blocked as this could cause the codes to show.
You maybe able to diagnose that via the exhaust if it seems restricted (flow) .?

Both sensors share the heater circuit which are wired in parallel so fault shows on one or the other or both. Had exactly the same on father-in-laws. Changed the front sensor and cleared fault but light came back on and fault code showed front sensor again?? Anyway found a thread on here about same thing and member who posted it said Nissan dealers always swap out both together. Did it. Fault cured.