Wife's 2012 Rio threw a code yesterday. Catalyst efficiency blah blah blah, P0420. Every car we've had that threw this code is when it gets cold. Why?
120k miles, no exhaust leaks and it burns no oil (polar opposite of mine that doesn't have this code). Sensor or cat likely issue? Being weather dependent makes me think cat.
I have the same code (P0420) in my Ford, I didn't realize manufacturers shared codes. (Do they have a sense of humor with 420 and exhaust?)
For the Ford 4.6, it's supposedly a bad right bank cat.
Mine is occasional, can't seem to find a pattern to it.
In reply to CyberEric :
The codes are standardized between all OEM's. That started in 1996 when OBDII came out.
The more you know! :)
Live with the light being on since it sounds like it is somewhat transient ... unless it is hugely apparent that the cat is not doing anything anymore, or unless you have to meet an emissions check to renew your registration.
Just a guess, but this is what I'd do:
I'd check live data to see what the temp sensors (water temp, intake temp, etc) are showing on a cold morning and then watch the change as it warms up to operating temp. Same goes for the O2 sensors.
It may be a bad sensor going out of range, or not moving, that's affecting air/fuel and causing a delay in getting the cat up to operating temp on cold mornings leading to wider swings in the downstream O2 readings.
In reply to einy (Forum Supporter) :
It may now be the case on newer cars, but I know when I had a '96 S-10 with a hollow cat, anytime the p0420 code was active my fuel economy took a dive.
In reply to No Time :
I'd love to but it's her car and she's gone before I even get out of bed. It's usually a "hey my car (.....). Can you fix it?"
I have similar issues on my truck. Also the right bank.
How do you check O2 sensors to see if it's that or the CAT? Upstream, downstream?
O2 sensors are not all that expensive or difficult to replace and are a wear item, it seems worth a try to replace just those and see if the code comes back.
In reply to Sonic :
They are a bit more of a chore on the backside of a slanted rearward engine and you don't have a lift. Plus to get two good sensors are going to be $200. And salt belt.
A cat efficiency code is almost always a cat. Cold weather might slow its warmup just enough ..
420 code when it's cold outside? Car just saying it's time to fire one up.
...I'll see myself out
You'll need to log in to post.
