OK, here I am two weeks later and the code is back. Admittedly, I was pushing it really hard--accelerating really hard up to 90mph driving on the interstate this morning. At some point I was at a stop light and noticed the engine light was on. I had the scanner in the glove compartment; connected it...

OK, my P0420 issue is finally resolved. All OBD2 readiness monitors passed by this morning, I was able to get an official smog test pass today and get the tag to prove I payed my taxes. See the previous post for details, but the highlights are: 1. Replacing the catalytic converter, both oxygen senso...

Whoa! The non-fouler trick may have "fixed" the car. I've driven the car three times so far, for at least 40 minutes total drive time. No set codes, no pending codes, catalytic converter and O2 sensor drive cycle monitors are showing ready. The evaporative system monitor is the only thing ...

https://www.autozone.com/ignition-tune-up-and-routine-maintenance/spark-plug-non-fouler/dorman-spark-plug-non-fouler-42006/720805_0_0 That's what I've done on Corolla and one Vibe, no more P0420. Thank you so much for the reply! I'll give this a try. Edit: OK, I see elsewhere in the forum and a ref...

tldr: I replaced the catalytic converter, both O2 sensors, intake manifold gasket, and spark plugs. I still have P0420. Please help! I replaced the upstream O2 sensor, reset the computer, and went for a test drive. The P0420 appears in the pending list after 5 minutes of driving. I replaced the dow...

OK, so it turns out that my code reader does have the option to plot a graph of a single parameter. I spent some time this morning getting plots of the O2 sensors. I'd appreciate it if someone could tell me what these plots suggest, although admittedly I'll most likely have replaced the sensors befo...

P0420 = bad cat 99% of the time. The code itself says the o2 sensor is working, as it detected the converter is below efficiency thresholds. OK, I just got done replacing the cat. I cleared the codes and took it for a test drive. Less than 5 minutes in and I have a pending P0420. Anybody got sugges...

edit: Replaced catalytic converter, and a number of other parts before fixing it with spark plug non-foulers. The fix lasted two weeks which was more than enough time to pass smog. The thread subject was also modified more than once. See subsequent posts in this thread for more details. Hi, I have a...

The noise will get louder on the outside bearing that gets loaded, as more weight is on that corner. So if you are turning left, and the noise gets louder, it is the passenger side bearing that is bad since more weight is loaded on that corner. That said, if you have already done one front bearing,...

The way you describe the noise is exactly what my Vibe was doing. It was a wheel bearing. I replaced them both and am now back to smooth cruising. SSizler, I don't suppose you remember which direction of turning made the noise louder? And which bearing was the actual failed bearing? Anyone: Is it p...

Story time: A couple years ago I had a valve cover gasket failure. Except I didn't know it until it fouled out an ignition module. The gasket failed at one of the spark plug wells and I suppose since it had never leaked or burned oil before I got out of the habit of checking the oil between changes...

...I didn't rotate the tires front to back. The purpose of rotating left to right was to try to localize the tires/wheels or eliminate them as the cause. Since turning to the right before the rotation caused the sound to get louder and turning to the right after the rotation also caused the sound t...

Welcome to GenVibe. Seeing how the martixowners site no longer exists hopefully we'll be your next best resource for Vibe/Matrix advise. I had a similar experience six months ago BUT mine was more definitive to the drivetrain. Not certain which side was the culprit, for the price of a second CV axl...

Did you try rotating tires front to back? Is your suspension and alignment in good shape? Motor mounts? Thanks for the taking the time to respond andrewclaus! An update to the original post: This morning I paid a bit more attention and I could feel it coming through the steering wheel and the floor...

When turning to the right while moving the sound gets louder, and when turning to the left while moving the sound gets quieter. Based on this I replaced the front driver's side wheel bearing. This did not affect the sound. I would venture to guess you should replace the passenger front wheel bearin...

tldr: 05 FWD with speed-dependent hum; steering changes intensity; already changed two wheel bearings, a CV axle, and transmission mount to no effect; finally fixed by replacing other front bearing despite elsewhere on the internet saying it wasn't the culprit. Hi, I have a 2005 Matrix XR with 260K ...