C2 Code 1.6 16C Eml Light On

[kipperfeet]

hi all , hoping someone can help. i have plugged obd scanner into car and its coming up with p0420 which is catalyst system efficiency below threshold. i have unplugged the precat lambda sensor and its reading 10ohms across the heater and 600mv on tickover, the postcat lambda is reading 15ohms on the heater and 300mv on tickover. i used to own a saxo vts which was seemed very fast compared to the same engined c2.was wondering if the cat could be blocked slightly. has anyone any thoughts.

[paul.h]

Welcome to the forum.

 

If you use your code reader and look at live data for the inlet and outlet lambda sensors, the inlet one should be constantly switching around 1.0 (which is then used in adjusting the fueling) and the outlet one should be steady. If the inlet is not switching it may need replacing. If the outlet one is switching like the inlet one then the cat needs replacing.

[kipperfeet]

hi paul, cheers for the reply.unfortunately my code reader isnt that good. however today i disconnected one lambda and another fault came up, so i  presumed it was probably working ok. i then disconnected the other one and this came up with another fault so i presumed that one was ok.

i then went in a pug forum and a few people mentioned replacing the crank sensor. i wasnt having it , but for the sake of £11.10 for a new one i gave it a go. it has worked, i cant believe it. fault cleared straight away. hope this helps someone else in the future.