I have p0133 and p0135fault codes showing on my octavia it says it's a slow response 02 sensor and 02 heater circuit I've only just bought as far as ino it has had a remap ,baileys dump valve ,and a rebel power pipes straight thru exhaust I wondered if having these mods could cause the fault codes or if it is just faulty sensors? Thanks in advance

The exhaust will cause O2 sensor faults if there is no CAT present. No CAT is also an instant MOT failure, something to keep in mind if you just got the car.

Ok thanks and yes I am wanting to put a cat on, but would it show both fault codes if it was the exhaust? Can do you know the location of the sensor on the car?

Got the car on a ramp today and it does have a cat and the exhaust looks strange it has a powerflow tip and back box but all the pipe work isn't stainless so not sure what's been done there