Technical Errors found: P0420-62 - Catalyser 1 - Signal compare failure

[Jussi69]

So occasionally get this error
500 1,4 100hp 2008
Errors found:
P0420-62 - Catalyser 1 - Signal compare failure

I believe its the lambda sensor after the catalyser - can someone confirm?

So its either the sensor that is faulty or the catalyser that is gone.

 

[steveras57]

Sounds like the sensor! as they are not that expensive you could just change it clear the fault codes and then re-scan!
are there any driveability issues? ,starting problems? rough running?, or idling problems!.

 

[Jussi69]

I believe this error is caused by the 2nd lambda after the cat - no impact to driveability. It occasionally comes back. 2nd lambda has been replaced recently prior I did not have this error. Now is there a way to delete 2nd lambda all together like in motorcycles you can buy these blockers that emulate the lambda signal.

 

[steveras57]

I have to say that thought that cat 1 signal meant PRE-cat- and signal 2 fail meant post cat! I might be wrong though! however if you was to swap out the pre -cat sensor as well you would know that they are (in theory) both good!.
If the error only showed up after the post cat sensor swap then you may have disturbed something when it was fitted, so check wiring /connectors for faults ! also though unlikely it is possible that the new sensor is faulty! but difficult to tell without trying another one!

 

[Jussi69]

Yes indeed the plan si to change the pre cat one as these are not expensive. Also to analyse the exhaust to see what that tells.

 

[John202020]

This "maybe" the correct pre cat sensor direct fit, check

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[steveras57]

let us know the results once you have done it please!

 

[puntodeltathema]

P0420 is about the two sensor signals not being "different enough" (also referred to as a cat efficiency error). It's not about a particular sensor per se (the reference to "Catalyser 1" is generic text and because there is a separate code (P0430) for a similar issue on any second cat, e.g. because a "V" engine is present - not relavant to a 500 ).

I'd probably try running a bottle of decent cat cleaner through before changing sensors. Though ultimately it may be the cat needs replacing.

Nick

Edit: I see you replaced the downstream sensor. What prompted this (and are you sure it is the right one, there are a number of different sensors for 500s and I'm pretty sure the 1.2 and 1.4 have different sensors).

 

[Jussi69]

Thanks - the cat might have suffered a little as when i was driving to the garage the cylinder 3 coil gave up maybe 3km prior resullting a massive misfire in the exhaust. Thtas why lambda 2 was replaced. And meybe I need to source a new cat as well. I assumed that the workshóp fitted right lambda, but will ask. they anyhow were able to fox the salespeed.

 

[steveras57]

I think your piggy -bank ran away and hid when it heard you say "new-cat"

 

[GettinBetter]

P0420 is about the two sensor signals not being "different enough"

That's how I read it, which is saying the CAT isn't working well enough, but as the cat is the most expensive part, you'd want to make sure both O2 sensors are within spec.... well I would anyway.