cel question=-

[jamesmetairie]

05 vibe, About 179000 miles on it . Had a cel light for a few years. Auto Zone always says it,s cat converter .

Recently noticed some vibrations when sitting at idle. Feels the same as when an ignition coil is malfunctioned .. But not as severe.

Question= can I go to a/z and get it scanned to see if other things are sending a code?

Does the cel system reveal such things?

[andrewclaus]

Yes, parts stores will still scan your codes. But the one time I had that done the guy made a mistake writing it down. Basic scanners are fairly inexpensive, so I got one. Also, there can be "pending codes" that won't light up the CEL.

If the CEL starts flashing, that' means a critical failure and to stop driving.

The system looks at electrical inputs and outputs. It may not see issues due to mechanical wear or lack of maintenance. A dirty fuel system, air filter, and/or MAF sensor can cause rough idle without throwing a code. A CAT code could be caused by piston ring failure and that could get worse.

[joatmon]

One of my Vibes kept throwing an evap control code, and I couldn't find the issue, didn't affect engine performance, and I live in a part of MD that doesn't require periodic emissions testing. I had a CEL code reader, and when the light came on, I checked the code, saw it was the same ones, and cleared it so I would know if something different ever came up. The car will set a code for any problem, having one already set doesn't prevent others from being set also, but if you've got one already, you won't notice another, unless, as andrewclaus said, its bad enough to make the light flash

There are a lot of options for code readers. Early on in genvibe time, ones called scangauge were popular, I got one. It was plug in but wired, kind of a clunky box, but it worked well. Have since got a tiny thing that bluetooths to a phone app. Guess that's what a decade or two of technology brings. But those of us here are apparently now a crowd that tends to have older cars, and older cars develop issues, and a code reader is a useful weapon in the battle. Even if you don't do any repairs yourself, nice to know whats going on and also helps to know if a repair shop is trying to scam you on a CEL repair.

It is possible that oil consumption can coat the gut of a converter and keep it from working well, and it could get bad enough to restrict flow through the cat to the point where it affects performance. Converters are pricey, that's why people steal them. I only replaced one in a VIbe, and I bought an exact fit bolt on from a GM dealer, back when they supported Vibes, but these days it would be cheaper to get some generic muffler shop to weld in a replacement. Later, on 2 Vibes and a Matrix, I cheated the P0420 away by using spark plug antifoulers to back the O2 sensor out of the exhaust stream (something described in several threads here at genvibe somewhere)

[jamesmetairie]

thanks guys.