I was driving into work yesterday morning. The road is trash there. Usually there's this spot in the road where right in the middle of the lane, there's an outcrop of asphalt that's raised about 2-3 inches above the asphalt above it due to weather damage or a tree root. Anyway, this particular morning, it seems like someone upset the outcrop and that caused a big chunk of asphalt to jut out even higher than usual. So of course, I drove over it thinking I'd still clear it. I ended up hitting it because I heard a loud bang/clunk, so loud that I actually almost pulled over on the spot.

I haven't been able to lift my car up and look at everything, but I did a quick peek under the car when I found parking and nothing stood out as being damaged or broken (nothing hanging onto the ground).

Then this morning, my check engine light comes on and thinking it's just a pesky P0446 EVAP code, I go to my scanner and clear it only to find a lovely P0420 catalyst efficiency low (bank 1).

I did some searching and found that leaving this code can eventually cause the car to stall.

So I'm wondering, how much time do I have before my car starts stalling out? I am hoping that the impact knocked the cat flanges open and that some hammering and bending can close up any gaps that were created in the impact. Worst case is there's a hole in my catalytic converter, or worse yet my catalytic converter has reached the end of its life at the exact same time that I bottom out on a broken piece of asphalt.

I could really use some pointers or help. I really don't want to end up on the side of the road on my way to, or from work.

 

Hello,

Really hard to tell anything without lifting the car up for a proper inspection, but for how the exhaust is placed in those cars, you much be one heck of a lucky bloke to avoid splitting the engine in half and hit a catalyst instead, especially considering that it must be a hit so precise that it didn't damage the exhaust enough for a sound to change, I once had a ... questionable pleasure of driving a car with a disintegrated catalyst, trust me, you would hear it.

In short, until proven otherwise, I would consider it a coincidence. First of all, look under the car as soon as you can, catalyst and said code may be the least of your concerns there, depending on how hard the hit was, and where the brunt of it went. If there is nothing obvious, here is a thread that explains how to diagnose Catalyst Efficiency Codes.

Hope this helps and best of luck!

 

Hi just wanted to update. I know it’s been a while but I took a better look under the car while I was changing my wheels, and what do you know, the exhaust got dented by the hit! Here’s a picture! Lmao.

Driver side:



Passenger side:



Another angle of the driver side dent:



Soooo I’m thinking the flow restriction is causing to O2 sensor to pick up more of… whatever it picks up, hah. To circumvent this I will be installing a spacer and possibly replacing the piping at some point.

 

Yes, I agree with you.

 

If the impact split a weld seam, and caused an exhaust leak, that will throw off the O2 sensor readings. I see a big gap in the exhaust flange in the bottom photo, at the bottom of the cat. Looks like left side. Check if bank 1 is on the left. You may want to have an exhaust shop straighten out your pipes and the flange.