Hello all

My daughter’s Peugeot (2007 – 1.4 16v petrol) has thrown up P0420 (Catalyst System Efficiency Below Threshold (Bank 1)) and in an attempt to understand this I’ve watched an awesome youtube vid on how Cats work.

As I understand it, the voltage on the PRE Cat sensor will fluctuate betwwen 0v – 1v and the POST Cat sensor should be a constant at around 0.65v.

I’ve attempted to use Torque to check these voltages although I don’t think I’ve been smart enough to work out which displays I need to look at.
I thought I found these displays as the following, but I’m getting fluctuating readings from both:

Pre Cat? “O2 1×1 V” (read 0v – 0.8v)
Post Cat? “02 1×2 V” (read 0v – 0.9v)

Can someone please help me understand which item in the display menu I should be looking at to get the voltage from the post cat sensor?

Thank you!

that’s what I thought, seems logical. But, that display is reading 0v – 0.9v with regular pulses.

I didn’t look at test results, I was looking at live data. From what I understand, it should be a constant voltage on that one.

I just found a vid on youtube on this very subject, and it shows the sensors that I selected graphed and the results on bank 1 sensor 2 are stable at around 0.6v.

My question was simply to find out if I was looking at the correct graphs, it seems I was.

…and I agree, sensor 2 matching sensor 1 means the cat ain’t doing anything.

…new cat.

thanks!