P0420 Catalyst System Low Efficiency ECM, PCM
well i got that last night,clear it today and drove from RI to CT and it didn't come back on, so hoping it was a 1 time thing. but what could set that

 

Got an aftermarket cat?

 

nope, mod are in vgarage

 

Moved

 

What could cause a Cat low efficiency code? Perhaps your Cat isn't working properly.

Warranty it.

 

if it comes back i will,but just drove over150 miles today and no light. but i am gonna take it in for that dam heater fan noise whens its on 1or 2

 

Fair enough, but if you're taking it in, I'd mention it to them while you're there. Worst thing they say is it isn't in memory and don't do anything about it. Good luck.

 

cat efficency means the cat isnt converting nox to n2 o2, carbon dioxide to carbon monxide, and HC to water and carbon monxide according to the computer, could be the cat, an o2 sensor, or engine controller or and exhaust leak, or an error code. if it comes back, then worry about it.

 

well the CEL light came back on, ill call the dealer 2morrow and bring it in and see what code it is this time.

 

Yeah it takes a lot of miles to get the code to come back on, the o2 sensor for the cat has to monitor for a while and i bet you if you had a tech 2 you would see the MV range for the o2 going all over the place.

 

wow my tech use to work for chrsyter. so first he blames my "aftermarket" exhaust cuz it had not res one it. lol umm its a GMPP exhaust so i flipped about that, then they didnt hear any noise from my heater fan so again i flipped, i mean wtf are all dealers stupid????

 

instead of flipping, you could have just politely asked him how a warrantied gm product would cause that particular code? and even if it IS because of the exhaust, which it's not, it's a warrantied product. so who cares? yelling and screaming and "flipping out" won't get you anywhere in life.

as far as the code, i've had it for months.

 

no they are saying is not covered its not a factory part. like GMPP is not real

 

the point is, ask them to explain to you how your exhaust, regardless of what exhaust it is would throw that code. basically they're just looking for an excuse to not do the work. this is why it's always best to go in as an informed customer. how abotu going to another dealer?

 

It's posts like these that make me wonder just how much GM gets away with due to uninformed customers...

 

they get away with alot. people don't know how to defend themselves because they don't know what to say or do with the dealer. i got a broken axle fixed under warranty with a 2.9, mounts, and a few other goodies on the car

majority of it is in your attitude, and you have to know a little bit about what you're talking about.

 

had a talk with the owner, he is havin them order a new cat,fan blower all under coverage

 

what noise does ur fan make anyways?

 

ticking noise on speed 1 and 2

 

mine makes noises on 2 but very quiet, hard to hear so i dont worry about it

 

lol u will when it stops workin, my friends 05 stop workin on speed 1

 

well after 2 days i got my cobalt back,they replace the blower thing and my cat.no noise on the fan anymore

 

well i got the same code again....what could cause this??