Catback exhaust P0420

[alhitch]

Hi

I’ve had the fault code P0420 on my type r which as I’ve read it’s a good chance the cat is on its way out.

However I have a piper catback exhaust fitted, but(excuse my naivety) would there not be a cat included in that system or might that system be causing the sensors to read wrong?

Either way what advice would you suggest to sort it, replace sensors, replace the cat or is it something stupid as fitting a spacer in the lambda?

Thanks for your help guys

Alex

 

[Krzys]

Cat-back systems start from the cat, they don't include one.

 

[SmegHead]

That catback exhaust on it's own won't affect the cat efficiency. As well as a knackered cat a P0420 could be something as simple as an exhaust leak letting air in before or near the 2nd sensor.
First thing to do is get the car in the air and check you actually have a cat fitted (you seem unsure!), no leaks and no obvious damage to the cat itself.

Theoretically you may also have a sports cat which might be getting the car through the MOT, but is not efficient enough to fool the 2nd sensor which is usually turned off on K100\KPro to avoid this problem, or as you say a spacer used which may or may not help you depending on your exact spec, so a run-down of you cars' engine\exhaust mods would be useful for further diagnosis along with problem history eg how long owned the car, recent problem or there since day one, any recent changes that coincided with the fault and so on.

 

[alhitch]

That catback exhaust on it's own won't affect the cat efficiency. As well as a knackered cat a P0420 could be something as simple as an exhaust leak letting air in before or near the 2nd sensor.
First thing to do is get the car in the air and check you actually have a cat fitted (you seem unsure!), no leaks and no obvious damage to the cat itself.

Theoretically you may also have a sports cat which might be getting the car through the MOT, but is not efficient enough to fool the 2nd sensor which is usually turned off on K100\KPro to avoid this problem, or as you say a spacer used which may or may not help you depending on your exact spec, so a run-down of you cars' engine\exhaust mods would be useful for further diagnosis along with problem history eg how long owned the car, recent problem or there since day one, any recent changes that coincided with the fault and so on.

I’ve had the car since November where it’s been sat in a garage while I’ve slowly took it apart, was bought as a project/track car and I’m just slowly working my way round it’s problems aha.

The car is standard as far as I’m aware just a catback and a k&n induction system, the previous owner had thought it had been mapped but couldn’t prove it and there is no sign of a k pro which makes me think it ain’t.

I’ll have a look for a leak once a few more parts arrive so I can turn the engine over again, would there be anyway of telling the difference between a sports cat/original cat? I’m sure it’s got one as there no signs it’s been cut out