Check Emissions message & light - hesitation - O2 Sensor? Which one?

[Tom1471]

Car felt very lump and hesitating under part throttle , then seemed to be fine, then again it hesitated worse - full throttle and higher revs it seemed to be fine again but then all of a sudden CHECK EMISSIONS light illumunated. #


OBD reader has 2 codes:


P0135 - 02 Sensor Heater Circuit (Bank 1 Sensor 1)

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)


I presume the O2 sensor needs replacing, but there's 2 as I understand it, 1 pre-cat and one after? - is there any way to know which one has failed and needs replacing?


If I drive the car in the meantime can it cause engine issues?


Thanks for any help in advance!


(Car has KTEC manifold and decat, if it's relevant)

 

[Foxspeed]

ban k 1 = first sensor the second sensor is used for odb2 monitoring and making sure sensor 1 is working right

if you know someone with an obd2 plug with live data check the lambda sensor voltages they should be up / down if they are slow to change then thats an issue

 

[Tom1471]

Thanks for the info. I'm using Torque (Pro) with an ELM327 OBD bluetooth device , I can't seem to see lambda sensor voltage as an option so I don't think the app or OBD device support it.

I'll order the first Lambda sensor and see if the code reappears after clearing.

Cheers

 

[199fico]

Were you able to solve this ?

I have the same symptoms, maybe even worse:

ERROR: P0141: O2 sensor heater circuit BANK 1 SENSOR 2 ?

I assume i have to change the second sensor ?

Thank you.

 

[Addison]

Were you able to solve this ?

I have the same symptoms, maybe even worse:

ERROR: P0141: O2 sensor heater circuit BANK 1 SENSOR 2 ?

I assume i have to change the second sensor ?

Thank you.

I had this on mine yesterday funnily enough. It is possible the second sensor will need changing, I cleared it in hope it was just a false reading so it may be worth doing that first. I've yet to have it come back up.