I scrape the underside of my car the other night by trying to carefully (obviously not enough) driving over a triangular speed bump at an apartment complex. I ended up scraping the underside of the car. It was located around the driver's side front area. I didn't notice the CEL as I drove home but I surely noticed in this morning.

Off the top of you guy's and gal's head, what could've caused this? I've had the pulleys, intake, and everything installed w/ no CEL ever activating until after this scrape.

The only thing I know that I did out of the ordinary is switch gas brand, from Chevron to 76 (premium).

Alex

 

Take a look at this sensor in the CAT

 

Expol -- I will definitely need to check that

Btw, these kind of scrapes, is the underside of the car "strong enough" to take that kind of scraping? I mean, the parts under there (minus that sensor), is it pretty durable in these conditions? I know there's road debris and all that but does scraping fall under that type of conditions those underside components shoudl handle?

alex

 

Expo is right the CAT is the lowest point on the car, you might have yanked the CAT sensor.

 

So, w/ that CAT sensor gone (let's say) is it dangerous to drive my car around? Things like go to the grocery store and other basic errands during the meantime? Or is this thing a must fix because your car will "explode" w/out this sensor?

alex

 

I don't think it will explode. But, your MPG could suck or something. You won't pass your emissions test.

Maybe it will improve the MPG, or add 40HP!!! :-)

 

Not a problem,

If it is that sensor (isn't that the stupidest place for it?) it is the 'secondary oxygen sensor'.

Its sole function is to monitor the catalysts' function, it sends a signal to the ECU when it detects the catalyst isn't working, but the ECU won't light a CEL until it gets the SECOND fault signal, that's why it came on the next day.

About $45 at PepBoys/Autozone, so about $200 dealer price.

If it is broken off, (and you don't go to the dealer) get a muffler shop to put the new one in, you need a 'special' tool to put it in.

S

 

Absolute crap location to place that sensor, but Mazda's not alone, it's happened on my previous ride..... just curious if there is a reason behind why they are placed in that particular location?

 

Well there are usually treaded into the front end of the CAT for a number of reasons. This one actually looks fairly serviceable. I have replaced a couple that were on the top or sides where there is no clearance. That was a brutal exercise even using a proper O2 sensor socket. You also need to worry about pinching the wires. I had the sensor heating element wire short to a heat shield once on a car which happened to share a fuse with the fuel pump. No fuel pump, no go and the short was rather hard to find . . . With the sensor gone the ECU will likely just run with a set of pre-sets for fuel mixture, this will let you get to where you are going but is not optimal for performance or emissions.

 

Any Bay Area ppl can help me out help me with this ... someone stole my jack stands from my apartment

alex