How do I know if my cat is shot?

[Boom Headshot]

Long story short, I developed a 0304 code: misfire in cyl 4. So I checked around, looked at some service records, turns out I hadn't done plugs and wires for 3 years. Did those, the gap on the plugs was hilarious. The misfire went away but then I got two more codes: 0135 and 0141. O2 sensors. I replaced those (reeked like gas when I pulled them) and while I was at it I did the coil pack on the corresponding cyl, just to be sure. The CEL for the sensors won't turn off on its own and it runs a bit rough. No new codes have surfaced. Cat time?

 

[plcfcng]

you can use one of those infared thermometers the out going temp should be higher I don't know by how much but it should be some where on the net.

 

[jgue467]

BEFORE I'd blow any cash on a cat, I'd Finish the Tune-up!! (meaning change remaining plugs, wires and test the other coils too). The problem is probably in there. Luck and enjoy the runner. :cowboy:

 

[Bad Luck]

Finish your tune-up, clear all dtc's and drive it. If your catalytic converter isn't functioning properly you'll through a P0420 catalytic converter efficiency code. Which indicates a poorly functioning catalytic converter, exhaust leak at or upstream of the 2nd oxygen sensor (downstream of catalytic converters), or a malfunctioning/lazy oxygen sensor downstream. You've already done both oxygen sensors so that narrows down your options. You can also read this thread from a few days ago: Clogged Cat?

 

[VernySanders]

I also have a misfire and am running quite rough due to the cat. Still waiting on my supplies to simulate the rear o2. Then it's time to delete the cats

 

[MaineRunna]

Long story short, I developed a 0304 code: misfire in cyl 4. So I checked around, looked at some service records, turns out I hadn't done plugs and wires for 3 years. Did those, the gap on the plugs was hilarious. The misfire went away but then I got two more codes: 0135 and 0141. O2 sensors. I replaced those (reeked like gas when I pulled them) and while I was at it I did the coil pack on the corresponding cyl, just to be sure. The CEL for the sensors won't turn off on its own and it runs a bit rough. No new codes have surfaced. Cat time?

How long did you drive it with the misfire? If it was a while you may have cooked your converter and possibly damaged the sensors, but both of those codes are for the O2 heater circuit. Can you watch engine sensor data end see how the two O2 sensors are reading?

 

[gamefreakgc]

I was going to be a smart aleck and post an image of a "cat shot" and was horrified by all the photos of cats with arrows sticking out of them. Don't do it.

 

[jbtvt]

I was going to be a smart aleck and post an image of a "cat shot" and was horrified by all the photos of cats with arrows sticking out of them. Don't do it.

I came here to say "shave it and check for holes"

But anyway, are you sure you changed the right oxygen sensors? Because if you did and you're still having a problem with their heaters you likely have a short in the wiring. Downstream O2 sensor won't affect driveability at all, only checks your emissions. As was said above, buy an OBD2 bluetooth dongle, download torque pro and check your O2 data (assuming you can on your engine, I never tried)

 

[Boom Headshot]

Miss came back, but only when the engine has warmed up. Bummer is that I can't tell which cylinder is missing because it won't throw a code. I don't think it's an injector because when it's missing, and I get on the gas, I get a flashing CEL, which means (correct me if I'm wrong) that there is gas in the cat.

The only CEL I get is for the O2 sensor circuits. So what are the odds that both of my O2 sensor circuits went bad at the same time? Are they on the same harness? Might be a bad connection there.

 

[Boom Headshot]

I also took a rubber hammer and beat on the cat for a few minutes. Aside from getting a little louder it doesn't seem to have changed anything.

 

[WWRD99]

To have 2 heater codes for the 02s can be a fuse that feeds the circuit...think it's the sensor fuse under the hood.

Sent from my SM-G955U using Tapatalk

 

[Boom Headshot]

To have 2 heater codes for the 02s can be a fuse that feeds the circuit...think it's the sensor fuse under the hood.

Sent from my SM-G955U using Tapatalk

Good info, thanks. I'll have to check that out.

UPDATE: Couldn't find a sensor fuse so I just checked them all, they're all fine, none broken. Checked all of the fuses inside as well, they're all good.

 

[Roberttt04]

If it’s not breathing then it’s safe to say your cat has been officially shot

 

[RandyBobandy]

try removing the pre cat o2 sensor and see if it's still running rough, if your cat is clogged taking the primary sensor out will allow it to breathe through the hole, you'll probably get a code from doing this but it should allow you to verify if the clogged cat is causing an issue

 

[VernySanders]

I've had my truck open headers for a couple weeks ( sounds like poo ) not daily driving it but I have driven it a couple times to different shops and to test my tundra brake upgrade. It has ran significantly better without that quarter million mile exhaust on it. Tomorrow I'm Installing a magnaflow 49 state cat that connects to the manifold and then running a pipe straight back to muffler. Already simulated the rear 02. Hope you find the solution. Mine was, in fact, the cats.

 

[Bad Luck]

I've had my truck open headers for a couple weeks ( sounds like poo ) not daily driving it but I have driven it a couple times to different shops and to test my tundra brake upgrade. It has ran significantly better without that quarter million mile exhaust on it. Tomorrow I'm Installing a magnaflow 49 state cat that connects to the manifold and then running a pipe straight back to muffler. Already simulated the rear 02. Hope you find the solution. Mine was, in fact, the cats.

Why are you simulating the oxygen sensor if you're installing a cat?

 

[VernySanders]

Why are you simulating the oxygen sensor if you're installing a cat?

My truck is from California so it has two cats. So if I only install the one it's still going to throw a light and sense that something's wrong. Plus if you sim the o2 as long as the resistance is good it will always work even if the heater element goes out.