Clueless girl here, advice appreciated.

My truck has the engine light on with the codes that say that the catalytic converters are both below the threshold. I am planing on replacing both of them but I have read online that sometimes it’s actually the o2 sensors that can throw that code. Or that replacing the converters with new ones won’t solve the problem causing the new converters to mess up too. I am really confused on to what to do first with my truck. Any help???

 

O2 sensors are cheap and easy. Were it my truck I'd do that first

 

X2. Use Denso brand.

 

Cats don't usually go just 'go bad' unless they have a ton of miles on them...if they're relatively young and gone bad then you want to found out why and solve that issue so you don't lose your new cats prematurely as well. A too lean or rich running engine will greatly reduce the lifespan of your cats, usually that's the reason they go out early.

 

If you have time, you can also try cleaning the Cat Converters before buying anything expensive - remove them (make sure you have new gaskets and hardware), dunk them in a rich Dawn detergent bath (I'd even let them soak overnight), dry them out, and reinstall. See if the issue clears.

 

Pretty common with the 4.0.
Try running some Sea Foam cleaner in the gas tank- cleans the cats out.Each one will run you about a grand a piece.
Also no aftermarket California approved cats currently available.

 

Check for exhaust leaks. My y-pipe leaks were it connects to the main cats and every now and then I get a cat efficiency code.

 

Well I have to admit. That's the first time I've heard that remedy.

 

2.7 also had TSBs for early cat failures. Mine failed at 13k miles.

 

Second for replacing o2 sensors.

 

Blue dawn. Has to be blue.

 

local dealer quote me 1200 a pair.

 

That is a great deal!

 

You didn't mention that the truck was running bad? If the catalytic converters were bad I'd expect it to affect the idle, if there clogged, they would get red hot.

It's very unlikely they are bad. I'd reset the codes, if you dont have an OBD reader, autozone can do it for you for free. Then drive it and see how long it takes for the code to be thrown again (if it does). If it throws the code again, try what the guys suggested above. Start with looking for exhaust leaks. Thats pretty easy, usually you can see some black residue where the gasket is leaking or you can hear a 'tick, tick, tick' sound from the gasket. Then, like stated above, sensors, etc.

Before you drop a huge amount of $$$$ it's worth the time to check everything else first.

 

This is pics of my current engine before install, you see the 'rusty' looking thing on the side of the engine? And the thing sticking out of it in the closeup pic? Look for that under your hood, it will be down towards the bottom towards the cab on the exhaust manifold. Check to make sure, on both sides, they are plugged in and the wires are not damaged.

 

Should be able to roll under the truck and take a peak too! My buddy has the same code going on in his corolla thats intermittent. We aint worrying about it till its inspection time.

 

Unless your in Cali, I'd reset codes in parking lot, get inspection while no codes thrown and ride on, lol!

 

I have a 2013 tacoma and there was a catalytic converter recall on it. Took mine in and got it replaced. Didn’t have any codes prior though...

 

I mean its only one sensor but for the time being its intermittent so screw it. Ride on!

 

Yup!